Map

map是RxJava中最简单的一个变换操作符了, 它的作用就是对上游发送的每一个事件应用一个函数, 使得每一个事件都按照指定的函数去变化. 用事件图表示如下:

图中map中的函数作用是将圆形事件转换为矩形事件, 从而导致下游接收到的事件就变为了矩形.用代码来表示这个例子就是:

创建一个bean

package tongxunlu.com.myapplication;

/**
 * Created by wangwei on 2018/8/30.
 */

public class TestBean {
    private int userAccountType = -1; //账号类型。1:管理员账号 2:普通账号
    private int roleID = -1;//账号所属角色ID
    private int employeeID = -1;//账号对应的员工ID
    private int businessType = -1;//账号对应的行业类型  1 美发 2足浴 3美容 5美甲
    private String userAccountName;//账号名称
    private int userAccountID = -1;//账号ID
    private String roleName;//角色名称

    public static final int BUS_TYPE_MEIFA = 1;
    public static final int BUS_TYPE_ZUYU = 2;
    public static final int BUS_TYPE_MEIRONG = 3;
    public static final int BUS_TYPE_MEIJIA = 5;


    public int getUserAccountType() {
        return userAccountType;
    }

    public void setUserAccountType(int userAccountType) {
        this.userAccountType = userAccountType;
    }

    public int getRoleID() {
        return roleID;
    }

    public void setRoleID(int roleID) {
        this.roleID = roleID;
    }

    public int getEmployeeID() {
        return employeeID;
    }

    public void setEmployeeID(int employeeID) {
        this.employeeID = employeeID;
    }

    public int getBusinessType() {
        return businessType;
    }

    public void setBusinessType(int businessType) {
        this.businessType = businessType;
    }

    public String getUserAccountName() {
        return userAccountName;
    }

    public void setUserAccountName(String userAccountName) {
        this.userAccountName = userAccountName;
    }

    public int getUserAccountID() {
        return userAccountID;
    }

    public void setUserAccountID(int userAccountID) {
        this.userAccountID = userAccountID;
    }

    public String getRoleName() {
        return roleName;
    }

    public void setRoleName(String roleName) {
        this.roleName = roleName;
    }

    //是否有房态
    public boolean hasRoom() {
        if (businessType == 2) {
            return true;
        }
        return false;
    }

}

本地新建一个字符串

{
  "businessType": 345,
  "employeeID": 0,
  "roleID": 2344,
  "roleName": "我是名字",
  "userAccountID": 4567897,
  "userAccountName": "wangwei",
  "userAccountType": 1
}

读取assert里面的字符串

    //从资源文件中获取分类json
    public static String getAssetsData(String path) {
        String result = "";
        try {
            //获取输入流
            InputStream mAssets = CoreApplication.getInstance().getAssets().open(path);
            //获取文件的字节数
            int lenght = mAssets.available();
            //创建byte数组
            byte[] buffer = new byte[lenght];
            //将文件中的数据写入到字节数组中
            mAssets.read(buffer);
            mAssets.close();
            result = new String(buffer);
            return result;
        } catch (IOException e) {
            e.printStackTrace();
            Log.e("fuck", e.getMessage());
            return result;
        }
    }

通过代码开始订阅

        Observable.create(new ObservableOnSubscribe<String>() {
                    @Override
                    public void subscribe(ObservableEmitter<String> emitter) throws Exception {
                        Log.w(TAG, "Observable--" + Thread.currentThread().getName());
                        emitter.onNext(mUserInfoJson);
                        emitter.onComplete();
                    }
                }).subscribeOn(Schedulers.io())
                        .observeOn(AndroidSchedulers.mainThread())
                        .map(new Function<String, TestBean>() {
                            @Override
                            public TestBean apply(String userString) throws Exception {
                                Log.w(TAG, "apply--" + Thread.currentThread().getName());
                                Gson gson = new Gson();
                                TestBean currentUseInfo = gson.fromJson(userString, TestBean.class);
                                return currentUseInfo;
                            }
                        }).subscribe(new Consumer<TestBean>() {
                    @Override
                    public void accept(TestBean s) throws Exception {
                        Log.w(TAG, "Observ--" + Thread.currentThread().getName());
                        Log.d(TAG, "accept---" + s.getUserAccountName());
                    }
                });

在上游我们发送的是字符串类型, 而在下游我们接收的是TestBean类型, 中间起转换作用的就是map操作符, 运行结果为:

W/MainActivity: Observable--RxCachedThreadScheduler-1
W/MainActivity: apply--main
W/MainActivity: apply--userString{
                 "businessType": 345,
                 "employeeID": 0,
                 "roleID": 2344,
                 "roleName": "我是名字",
                 "userAccountID": 4567897,
                 "userAccountName": "wangwei",
                 "userAccountType": 1
               }
W/MainActivity: Observ--main
D/MainActivity: accept---wangwei

通过Map, 可以将上游发来的事件转换为任意的类型, 可以是一个Object, 也可以是一个集合, 如此强大的操作符快去试试吧。