LeanCloud Learning Course

获取第一行

AVQuery<Studentq = AVObject.getQuery(Student.class);
Student student = q.getFirst();

根据已有ObjectID获取数据

Student student = AVObject.createWithoutData(Student.class, "objectId");
AVObject fetched = student.fetch();

保存文件

AVFile avatar = new AVFile("avatar", getAvatarBytes());
Student student = new Student();
student.setName("name");
student.setAvatar(avatar);
student.save();

序列化

//将对象序列化成字符串
Student student = getFirstStudent();
String s = student.toString();

//从字符串中解析对象
AVObject parseObject = AVObject.parseAVObject(s);

AVObject已经实现了Parcelable接口

public class AVObject implements Parcelable {
......
}

......

Intent intent = new Intent();
intent.putExtra("student", student);

Student intentStudent = intent.getParcelableExtra("student");

离线保存对象
```
public void saveEventually(SaveCallback callback) {
......
}

......

Student student = new Student();
student.setName("testOfflineSave");
student.saveEventually();
```
适用于用户并不关心具体保存到服务器的具体时间，或者数据并不需要时常与服务器发生交互时，可以使用本方法在网络请求遇到异常时，AVOS Cloud会将此类请求保存到本地，等到网络回复正常或者排除故障以后再发送请求被保存下来的请求会按照初始的发送顺序进行发送
由于保存的时间无法确定，回调发生时可能已经超出了原来的运行环境，即便发生也没有意义，所以不鼓励用户saveEventually中传入callback

整形字段的自增方法

student.increment("age", 1);
student.save();

any字段可以存储任意类型

//Any 字段保存为了数字
student.setAny(1);
student.save();

//Any 字段保存为了字符串
student.setAny("hello");
student.save();

//Any 字段保存为了Map
HashMap<String, Object> map = new HashMap<>();
map.put("like", "swimming");
student.setAny(map);
student.save();

student.getAny()

讲某个字段所有数据置空
```
student.remove("age");
student.save();
```

ARRAY类型字段添加或移除数据

List<String> hobbies = new ArrayList<>();
hobbies.add("running");
hobbies.add("fly");
student.addAll("hobbies", hobbies);
student.save();

......

student.add("hobbies", "swimming");
student.save();

......

List<String> removeHobbies = new ArrayList<>();
removeHobbies.add("swimming");
student.removeAll("hobbies", removeHobbies);
student.save();

......

//添加唯一数据，存在就覆盖，保证唯一性
student.addUnique("hobbies", "swimming");
student.save();

添加多条数据，批量保存

List<Student> students = new ArrayList<>();
for (int i = 0; i < 5; i++) {
    Student student = new Student();
    student.setName(i + "");
    student.setAge(i + 10);
    students.add(student);
}
AVObject.saveAll(students);

......

List<Student> students = new ArrayList<>();
    for (int i = 0; i < 5; i++) {
        Student student = new Student();
        student.setName(i + "");
        AVFile avatar = new AVFile("avatar" + i, getAvatarBytes());
        student.setAvatar(avatar);
        students.add(student);
    }
    AVObject.saveAll(students);

修改多条数据，批量修改

for (Student student : students) {
    student.setName("testBatchUpdate");
}
AVObject.saveAll(students);

删除多条数据，批量删除
```
AVObject.deleteAll(students);
```

从ARRAY类型字段获取数据

AVObject myObject = new AVObject("Student");//新建AVObject对象会自动生成ObjectID
for (int i = 0; i < 5; ++i) {
    myObject.add("array", i);
}
myObject.save();

AVQuery<AVObject> query = AVQuery.getQuery("Student");
AVObject result = query.get(myObject.getObjectId());
List<Number> array = result.getList("array");

查询全部数据

AVQuery<Student> query = AVQuery.getQuery(Student.class);
List<Student> students = query.find();

获取第一条记录
```
Student student = query.getFirst();
```

限制记录行数

query.limit(2);
List<Student> students = query.find();

递减，降序

query.orderByDescending("createdAt");
query.skip(3);
Student first = query.getFirst();

递增，升序

query.orderByAscending("createdAt").limit(5);

条件查询，AND查询

query.whereNotEqualTo(Student.NAME, "Mike");
// 默认就是 And
query.whereStartsWith(Student.NAME, "M");

条件查询，OR查询

query1.whereEqualTo(Student.NAME, "Mike");
query2.whereStartsWith(Student.NAME, "J");

List<AVQuery<Student>> queries = new ArrayList<>();
queries.add(query1);
queries.add(query2);

AVQuery<Student> query = AVQuery.or(queries);
List<Student> students = query.find();

二次排序

query.orderByDescending(Student.NAME)
        .addDescendingOrder(Student.AGE)
        .limit(5);
List<Student> students = query.find();

ARRAY类型字段的查询匹配

query.whereSizeEqual("hobbies", 2).limit(10);

某个字段的多条件匹配

//字符匹配
query.whereStartsWith("name", "M")
.whereEndsWith("name", "e")
.whereContains("name", "i");

......

//包含其中之一
query.whereContainedIn("name", Arrays.asList("Mike", "Jane"));
List<Student> students = query.find();

......

//全部包含
query.whereContainsAll("hobbies", Arrays.asList("swimming", "running"));
List<Student> students = query.find();

通过正则表达式查询匹配
```
query.whereMatches("name", "^M.*");
```

开启全局省流量模式

// 应该放在 Application 的 onCreate 中，开启全局省流量模式
AVOSCloud.setLastModifyEnabled(true);

Student student = getFirstStudent();

// 此处服务器应该返回了所有数据
AVQuery<Student> q = AVQuery.getQuery(Student.class);
Student student1 = q.get(student.getObjectId());
log("从服务器获取了对象：" + prettyJSON(student1));

// 客户端把该对象的udpatedAt传给服务器，服务器判断对象未改变，于是返回 304 和空数据，客户端返回本地缓存的数据，节省流量
Student student2 = q.get(student.getObjectId());

......

q.limit(5);
// 此处服务器应该返回了所有数据
List<Student> students = q.find();

// 服务器记录表的修改时间，如果两次查询之间表未被修改且参数一样，则以下查询将从本地缓存获取数据
List<Student> students1 = q.find();

设置查询策略，本地缓存或网络

AVQuery<Student> q = AVQuery.getQuery(Student.class);

//1.CACHE_THEN_NETWORK

//查询首先尝试从缓存中获取，然后再从网络获取。在这种情况下，FindCallback 会被实际调用两次：
//首先是缓存的结果，其次是网络查询的结果。这个缓存策略只能用在异步的 findInBackground 方法中。
q.setCachePolicy(AVQuery.CachePolicy.CACHE_THEN_NETWORK);
// 单位毫秒
q.setMaxCacheAge(1000 * 60 * 60); // 一小时
q.limit(1);
q.findInBackground(new FindCallback<Student>() {
  int count = 0;

  @Override
  public void done(List<Student> list, AVException e) {
      if (count == 0) {
        log("第一次从缓存中获取了结果：" + prettyJSON(list));
    } else {
        log("第二次从网络获取了结果：" + prettyJSON(list));
    }
    count++;
  }
});

    ......

//2.CACHE_ELSE_NETWORK

    //查询首先尝试从缓存中获取，如果失败，则从网络获取，如果两者都失败，则引发一个 AVException。
    q.setCachePolicy(AVQuery.CachePolicy.CACHE_ELSE_NETWORK);
    // 单位毫秒
    q.setMaxCacheAge(1000 * 60 * 60); // 一小时
    q.limit(1);
    if (q.hasCachedResult()) {
      log("有本地缓存，将从本地获取");
    } else {
      log("无本地缓存，将从服务器获取");
    }
    List<Student> students = q.find();

    ......

//3.NETWORK_ELSE_CACHE

    //查询首先尝试从网络获取，如果失败，则从缓存中查找；如果两者都失败，则应发一个 AVException。
    q.setCachePolicy(AVQuery.CachePolicy.NETWORK_ELSE_CACHE);
    // 单位毫秒
    q.setMaxCacheAge(1000 * 60 * 60); // 一小时
    q.limit(1);
    if (q.hasCachedResult()) {
      log("有本地缓存，无网络时将从本地获取");
    } else {
      log("无本地缓存，将从服务器获取");
    }

    ......

//4.NETWORK_ONLY

    //查询不走缓存，从网路中获取，但是查询结果会写入缓存。
    q.setCachePolicy(AVQuery.CachePolicy.NETWORK_ONLY);
    // 单位毫秒
    q.setMaxCacheAge(1000 * 60 * 60); // 一小时
    q.limit(1);
    if (q.hasCachedResult()) {
      log("有本地缓存，但无视之");
    } else {
      log("无本地缓存，也无视之");
    }

    ......

//5.CACHE_ONLY

    //查询只从缓存获取，不走网络。如果缓存中没有结果，引发一个 AVException。
    q.setCachePolicy(AVQuery.CachePolicy.CACHE_ONLY);
    // 单位毫秒
    q.setMaxCacheAge(1000 * 60 * 60); // 一小时
    q.limit(1);
    if (q.hasCachedResult()) {
      log("有本地缓存，将从本地获取结果");
    } else {
      log("无本地缓存，将抛出异常，请先运行上一个例子，从网络获取结果保存到本地");
    }

    ......

//6.IGNORE_CACHE

    //默认的缓存策略，查询不走缓存，查询结果也不存储在缓存。
    log("此策略才网络获取结果，并不保存结果到本地");
    q.setCachePolicy(AVQuery.CachePolicy.IGNORE_CACHE);
    // 单位毫秒
    q.setMaxCacheAge(1000 * 60 * 60); // 一小时
    q.limit(1);

清除缓存

//清除当前查询缓存
AVQuery<Student> q = AVQuery.getQuery(Student.class);
q.limit(1);
q.clearCachedResult();

......

//清除所有缓存
AVQuery.clearAllCachedResults();
log("已删除所有的缓存");

whereMatchesKeyInQuery的使用，相应的有whereDoesNotMatchKeyInQuery

//Add a constraint to the query that requires a particular key's value matches a value for a key in the results
//of another AVQuery
//当前查询的某个字段与另外一个查询的某个字段的值相匹配
AVQuery q1 = AVQuery.getQuery("Person");

AVQuery q2 = AVQuery.getQuery("Something");
q2.whereMatchesKeyInQuery("belongTo", "name", q1);

注册用户

AVUser user = new AVUser();
user.setUsername("waylanpunch");
user.setPassword("111111");
user.signUp();
Assert.assertFalse(user.getObjectId().isEmpty());
String username = user.getUsername();

AVUser.logOut();
AVUser.logInInBackground(username, password, new LogInCallback<AVUser>() {
      @Override
      public void done(AVUser avUser, AVException e) {
        if (e != null) {
              log(e.getMessage());
        } else {
              log("登录成功 user：" + avUser.toString());
        }
    }
});

当前已登录的用户
```
AVUser user = AVUser.getCurrentUser();
```
注销当前已登录的用户
```
AVUser.logOut();
```

删除当前已登录的用户

user.delete();
  log("已删除当前用户");

修改用户数据

AVQuery<AVUser> q = AVUser.getQuery();
AVUser first = q.getFirst();
log("获取了一个用户，但未登录该用户");
first.put("city", "ShangHai");
try {
  first.save();
} catch (AVException e) {
  if (e.getCode() == AVException.SESSION_MISSING) {
    log("尝试修改未登录用户的数据，发生错误：" + e.getMessage());
  } else {
    throw e;
  }
}
log("结论：不能修改未登录用户的数据");

......

//修改密码
user.updatePassword(oldPassword, newPassword);

验证注册用户手机号码

// 请在网站勾选 "验证注册用户手机号码" 选项，否则不会发送验证短信
final AVUser user = new AVUser();
user.setUsername("test");
user.setPassword("test");
user.setMobilePhoneNumber("15866778899");
user.signUpInBackground(new SignUpCallback() {
      @Override
      public void done(AVException e) {
        if (e == null) {
              AVUser.verifyMobilePhoneInBackground("verifycode", new AVMobilePhoneVerifyCallback() {
                @Override
                public void done(AVException e) {
                      if (e == null) {
                        log("注册成功, user:" + user);
                      }
                   }
            });
        }
      }
});

输入手机号码+密码登录

AVUser.loginByMobilePhoneNumberInBackground("15866778899", demoPassword, new LogInCallback<AVUser>() {
      @Override
      public void done(AVUser avUser, AVException e) {
        if (e == null) {
          log("登录成功, user:" + avUser);
        }
      }
});

输入手机号码+验证码登录

AVUser.requestLoginSmsCodeInBackground("15866778899", new RequestMobileCodeCallback() {
  @Override
  public void done(AVException e) {
    if (e == null) {
          AVUser.loginBySMSCodeInBackground("15866778899", smsCode, new LogInCallback<AVUser>() {
            @Override
            public void done(AVUser avUser, AVException e) {
              if (e == null) {
                log("登录成功, user: " + avUser);
              }
            }
          });
    }
  }
});

使用手机号码重置密码

AVUser.requestPasswordResetBySmsCodeInBackground("15866778899", new RequestMobileCodeCallback() {
  @Override
  public void done(AVException e) {
    if (e == null) {
          final String newPassword = "abcdefg";
          AVUser.resetPasswordBySmsCodeInBackground(smsCode, newPassword, new UpdatePasswordCallback() {
            @Override
            public void done(AVException e) {
              if (e == null) {
                log("密码更改成功，新密码 " + newPassword);
                log("试着用手机号和新密码登录吧");
              }
            }
          });
    }
  }
});

邮箱验证

//请确认控制台已开启注册时开启邮箱验证，这样才能收到验证邮件
final AVUser user = new AVUser();
user.setUsername(text);
user.setPassword(demoPassword);
user.setEmail(text);
user.signUpInBackground(new SignUpCallback() {
  @Override
  public void done(AVException e) {
    if (e == null) {
      log("注册成功，user: " + user);
    }
  }
});

邮箱登录

AVUser.logInInBackground("waylanpunch@gmail.com", "testpassword", new LogInCallback<AVUser>() {
  @Override
  public void done(AVUser avUser, AVException e) {
    if (e == null) {
      log("登录成功 user:" + avUser);
    }
  }
});

使用邮箱进行密码重置

AVUser.requestPasswordResetInBackground(text, new RequestPasswordResetCallback() {
  @Override
  public void done(AVException e) {
    if (e == null) {
      log("重置密码的邮件已发送到邮箱 " + text);
    }
  }
});

匿名登录

AVAnonymousUtils.logIn(new LogInCallback<AVUser>() {
      @Override
      public void done(AVUser avUser, AVException e) {
        if (e == null) {
              log("创建了一个匿名用户并登录，user:" + avUser);
        }
      }
});

文件上传

//文件转换成字节数组
byte[] data = DemoUtils.readFile(file);
final AVFile avFile = new AVFile(file.getName(), data);
avFile.saveInBackground(new SaveCallback() {
  @Override
  public void done(AVException e) {
    if (e == null) {
      fileUrl = avFile.getUrl();
      objectId = avFile.getObjectId();
      log("文件上传成功 url:" + fileUrl);
    } else {
      log(e.getMessage());
    }
  }
}, new ProgressCallback() {
  @Override
  public void done(Integer percentDone) {
    log("uploading: " + percentDone);
  }
});

文件下载

AVFile avFile = new AVFile("my_download_file", fileUrl, null);
byte[] bytes = avFile.getData();
log("下载文件完毕，总字节数：" + bytes.length);

文件删除

// 需要控制台开启权限
AVFile avFile = AVFile.withObjectId(objectId);
avFile.delete();

根据文件绝对路径上传

File tmpFile = ......
AVFile file = AVFile.withAbsoluteLocalPath("filename", tmpFile.getAbsolutePath());
file.save();
log("从文件的路径中构造了 AVFile，并保存成功。file:" + toString(file));

直接上传文件

File tmpFile = ......

AVFile file = AVFile.withFile("filename", tmpFile);
file.save();
log("用文件构造了 AVFile，并保存成功。file:" + toString(file));

AVObject转换成AVFile

AVQuery<AVObject> q = new AVQuery<>("_File");
AVObject first = q.getFirst();
log("获取了文件 AVObject：" + first);

AVFile file = AVFile.withAVObject(first);

......

//根据ObjectId转换
AVFile file = AVFile.withObjectId(first.getObjectId());

修改AVFile元数据

Bitmap bitmap = ......
bytes = ......bitmap......

AVFile file = new AVFile("filename", bytes);
file.addMetaData("width", bitmap.getWidth());
file.addMetaData("height", bitmap.getHeight());
file.save();

AVFile获取图片缩略图

AVFile avatar = ......
String url = avatar.getThumbnailUrl(true, 200, 200);
log("最大宽度为200 、最大高度为200的缩略图 url:" + url);
//[http://docs.qiniu.com/api/v6/image-process.html](http://docs.qiniu.com/api/v6/image-process.html "七牛文档")
log("其它图片处理见七牛文档");

POINTER类型存储另外一个对象一个实例的ObjectId

AVObject post = new AVObject("Post");
post.put("author", user);
post.save();

ARRAY类型存储另外一个对象多个实例的ObjectId

AVObject post = new AVObject("Post");
post.addAll("likes", users);
post.save();

：注意add与put的区别，一个是在原ARRAY数组末尾新增，一个是直接赋值

add(java.lang.String key, java.lang.Object value)
//Atomically adds an object to the end of the array associated with a given key.

put(java.lang.String key, java.lang.Object value)
//Add a key-value pair to this object.

：ARRAY可以存储多个POINTER类型

联表查询

//返回的数据将只包含ClassName和ObjectId
AVQuery<Post> query = AVQuery.getQuery("Post");
query.whereExists("likes");
log("将不包含 likes 字段的具体数据");
Post first = query.getFirst();

......

//返回的数据除了ClassName和ObjectId字段，还包含其他所有字段
query.whereExists(Post.LIKES);
log("让返回结果包含了 likes 字段的具体数据，不单单是赞的人的 objectId");
query.include(Post.LIKES);
Post first = query.getFirst();

：注意

POINTER ： 一对一的关系
ARRAY ： 一对多的关系
AVRelation ：多对多的关系

AVRelation类型的使用，添加数据

Post post = query1.getFirst();
Student student = query2.getFirst();

AVRelation<Student> rewardStudents = post.getRelation("rewards");
rewardStudents.add(student);
post.save();

AVRelation类型的使用，移除数据

rewardStudents.remove(student);
post.save();

AVRelation类型的使用，查询数据

AVRelation<Student> students = post.getRelation("rewards");
AVQuery<Student> query = students.getQuery();
List<Student> stuList = query.find();

......

int count = query.count();

......

AVQuery<Post> postQuery = AVRelation.reverseQuery(Post.class, "rewards", student);
List<Post> posts = postQuery.find();

：注意，reverseQuery(java.lang.Class<M> theParentClazz, java.lang.String relationKey, AVObject child)
Create a query that can be used to query the parent objects in this relation.

类的继承，创建一个类SubUser继承自AVUser

public class SubUser extends AVUser {
    public static final Creator CREATOR = AVObjectCreator.instance;
    ......
}

：注意，SubUser继承自AVUser类

Armor armor = new Armor();
armor.setDisplayName("avos cloud demo object.");
armor.setBroken(false);
armor.save();

SubUser subUser = new SubUser();
String nickName = "testSignupSubUser";
subUser.setUsername(username);
subUser.setPassword(password);
subUser.setNickName(nickName);
subUser.setArmor(armor);
subUser.signUp();

SubUser cloudUser = AVUser.logIn(username, password, SubUser.class);
AVUser currentUser = AVUser.getCurrentUser();

......

//可以利用创建的子类SubUser登录，因为SubUser继承了AVUser所有属性和方法
SubUser.logInInBackground(username, password, new LogInCallback<AVUser>() {
      @Override
      public void done(AVUser avUser, AVException e) {
            AVUser currentUser = AVUser.getCurrentUser();
            Assert.assertTrue(currentUser instanceof SubUser);//Error
      }
});

：注意，Armor继承自AVObject类。

public class Armor extends AVObject {
      public static final Creator CREATOR = AVObjectCreator.instance;
    ......
}

使用SQL语句查询

//1. select

String cql = "select * from _User";
AVCloudQueryResult result = AVQuery.doCloudQuery(cql);

//AVCloudQueryResult以Json对象展示

result:[{
        "username": "p1nrxk2393jpi8twib0f0wwpu",
            "authData": {
                "anonymous": {
                    "id": "nmey8BRBOHXJLNQnjWw0LqB"
                 }
             },
         "emailVerified": false,
         "className": "_User",
         "mobilePhoneVerified": false,
         "updatedAt": "2016-04-05T05:28:29.189Z",
         "createdAt": "2016-04-05T05:28:29.189Z",
         "objectId": "57034cfd71cfe4005cd64e05"
     },{
         "emailVerified": false,
         "className": "_User",
         "mobilePhoneVerified": false,
         "username": "XiaoMing",
         "updatedAt": "2016-04-05T05:28:45.473Z",
         "createdAt": "2016-04-05T05:28:45.473Z",
         "objectId": "57034d0d5bbb50004dc9f001"
    },
    ......
    }]

......

//2. count

String cql = "select count(*) from _User";
AVCloudQueryResult result = AVQuery.doCloudQuery(cql);

{"results":[],"className":"_User","count":19}

......

//3. where

String cql = String.format("select * from _User where username in (?,?)");
AVCloudQueryResult result = AVQuery.doCloudQuery(cql, "test1", "test2");

......

//4. order by

String cql = String.format("select * from _User where createdAt < date(?) order by createdAt limit ?");
AVCloudQueryResult result = AVQuery.doCloudQuery(cql, "2016-05-01T00:00:00.0000Z", 3);

//AVCloudQueryResult以Json对象展示

result:[{
    "username": "p1nrxk2393jpi8twib0f0wwpu",
    "authData": {
        "anonymous": {
            "id": "nmey8BRBOHXJLNQnjWw0LqB"
        }
    },
    "emailVerified": false,
    "className": "_User",
    "mobilePhoneVerified": false,
    "updatedAt": "2016-04-05T05:28:29.189Z",
    "createdAt": "2016-04-05T05:28:29.189Z",
    "objectId": "57034cfd71cfe4005cd64e05"
    },{
    "emailVerified": false,
    "className": "_User",
    "mobilePhoneVerified": false,
    "username": "XiaoMing",
    "updatedAt": "2016-04-05T05:28:45.473Z",
    "createdAt": "2016-04-05T05:28:45.473Z",
    "objectId": "57034d0d5bbb50004dc9f001"
    },{
    "username": "9lsrmw91febck0fduf81o9fq9",
    "authData": {
        "anonymous": {
            "id": "zwAzy6L4MGVgsIhbmQLWMXB"
        }
    },
    "emailVerified": false,
    "className": "_User",
    "mobilePhoneVerified": false,
    "updatedAt": "2016-04-06T01:01:59.100Z",
    "createdAt": "2016-04-06T01:01:53.809Z",
    "objectId": "57046001128fe100524f097d"
    },]

获取服务器时间
```
Date date = AVOSCloud.getServerDate();
```

设置网络响应时长

// 得放到 Application 里
AVOSCloud.setNetworkTimeout(10);