Day04 Application 的使用

Application：
1.全局的对象，随着应用程序的销毁而销毁
2.使用Application在多个页面传递数据
使用场景：
A页面产生了数据， B , C, D页面想要去使用它
操作步骤：
1.创建子类 class MyApplication extends Application
2.在子类中创建属性，就是要传递的数据，设置 get /set方法
3. 在清单文件Androidmanifest.xml中的

android:name="com.yz.day05_04_applicationpassvalue.MyApplication"

1. 获取全局对象

MyApplication application = (MyApplication) getApplication();

5.传递数据
application.setXXX();//设置内容
application.getXXX();//获取内容

二、实例演示

MyApplication.java

package com.yztc.day0703_wang_04;import android.app.Application;/** * Created by My on 2016/7/3. */public class MyApplication extends Application{    private String name;    private String password;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }}

第二步：
在Androidmanifest.xml中注册

 <application        android:name=".MyApplication"

第三步：

package com.yztc.day0703_wang_04;import android.content.Intent;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.text.TextUtils;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends AppCompatActivity {    private EditText et_name,et_password;    private Button btn_login;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initComponent();        btn_login.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                String name = et_name.getText().toString();                String password = et_password.getText().toString();                if (TextUtils.isEmpty(name) || TextUtils.isEmpty(password)){                    Toast.makeText(MainActivity.this,"用户名或密码输入为空",Toast.LENGTH_SHORT).show();                }else {                    MyApplication application = (MyApplication) getApplication();                    application.setName(name);                    application.setPassword(password);                    startActivity(new Intent(MainActivity.this,Main2Activity.class));                }            }        });    }    public void initComponent(){        et_name = (EditText) findViewById(R.id.et_name);        et_password = (EditText) findViewById(R.id.et_password);        btn_login = (Button) findViewById(R.id.btn_login);    }}

接收共享数据页面处理：

package com.yztc.day0703_wang_04;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.widget.TextView;public class Main2Activity extends AppCompatActivity {    private TextView tv_show;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main2);        MyApplication app = (MyApplication) getApplication();        tv_show= (TextView) findViewById(R.id.tv_show);        tv_show.setText(String.format("name=%s\npassword=%s\n",app.getName(),app.getPassword()));    }}