Intent传参数

Intent 是Android 程序中各组件之间进行交互的一种重要方式，它不仅可以指明当前组
件想要执行的动作，还可以在不同组件之间传递数据。Intent 一般可被用于启动活动、启动
服务、以及发送广播等场景

   // A activity调用
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       // setContentView(R.layout.activity_main);  // 创建视图
        setContentView(R.layout.my_layout);
        // 找到对应的button来监听事件
        findViewById(R.id.butStartAnotherAty).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(MainActivity.this, AnotherAty.class);
                i.putExtra("data", "hello word");  // 使用Intent来传参
                startActivity(i);
            }
        });
        System.out.println("onCreate");
    }

    //B activity 通过Intent来获取值，并显示在textView上面
    private TextView tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_another_aty);

        Intent i = getIntent();  //直接获取传过来的intent
        tv = (TextView)findViewById(R.id.textView);
        tv.setText(i.getStringExtra("data"));
    }

// 如果数据比较多，可以通过 Bundle  数据包来传递数据

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       // setContentView(R.layout.activity_main);  // 创建视图
        setContentView(R.layout.my_layout);
        // 找到对应的button来监听事件
        findViewById(R.id.butStartAnotherAty).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(MainActivity.this, AnotherAty.class);
                //i.putExtra("data", "hello word");  // 使用Intent来传参
                Bundle b = new Bundle();  // 打包数据
                b.putString("name", "chengzhier");
                b.putInt("age", 2);

                i.putExtras(b);
                startActivity(i);
            }
        });
        System.out.println("onCreate");
    }

private TextView tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_another_aty);

        Intent i = getIntent();  //直接获取传过来的intent
        tv = (TextView)findViewById(R.id.textView);

        //i.getStringExtra("data")
        Bundle data = i.getExtras();
        String s = String.format("name=%s, age=%d", data.getString("name"), data.getInt("age"));
        tv.setText(s);
    }

// 传递一个对象 java 自带的 Serializable 虚拟化

// User类
public class User implements Serializable{  //让这个对象序列化
    private String name;
    private int age;

    public User(int age, String name ) {
        this.age = age;
        this.name = name;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public String getName() {
        return name;
    }
}

// A activity
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       // setContentView(R.layout.activity_main);  // 创建视图
        setContentView(R.layout.my_layout);
        // 找到对应的button来监听事件
        findViewById(R.id.butStartAnotherAty).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(MainActivity.this, AnotherAty.class);

                i.putExtra("user", new User(2, "zh"));

                startActivity(i);
            }
        });
        System.out.println("onCreate");
    }

// B activiry
 private TextView tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_another_aty);

        Intent i = getIntent();  //直接获取传过来的intent
        tv = (TextView)findViewById(R.id.textView);
        User u = (User)i.getSerializableExtra("user");  //取出来

        String s = String.format("测试11name=%s, age=%d", u.getName(), u.getAge());
        tv.setText(s);
    }

//传递一个对象 安卓专门的Parcelable虚拟化

/**
 * Created by ZhouXiaoHai on 2016/9/8.
    User 类
 */
public class User implements Parcelable{  // 安卓自带的序列化
    private int age;
    private String name;
    private String dogName;

    public void setDogName(String dogName) {
        this.dogName = dogName;
    }

    public String getDogName() {
        return dogName;
    }

    public User(int age, String name, String dogName) {
        this.age = age;
        this.name = name;
        this.dogName = dogName;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public String getName() {
        return name;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {  // 必须要写的 接口 Parcelable 的方法
        // 这个一定要按变量顺序写
        dest.writeInt(getAge());
        dest.writeString(getName());
        dest.writeString(getDogName());
    }

    public static final Creator<User> CREATOR = new Creator<User>() {
        @Override
        public User createFromParcel(Parcel source) {
            // 这个一定要按变量顺序写
            return new User( source.readInt(), source.readString(), source.readString());
        }

        @Override
        public User[] newArray(int size) {
            return new User[size];
        }
    };
}

//A activity
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       // setContentView(R.layout.activity_main);  // 创建视图
        setContentView(R.layout.my_layout);
        // 找到对应的button来监听事件
        findViewById(R.id.butStartAnotherAty).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = new Intent(MainActivity.this, AnotherAty.class);

                i.putExtra("user", new User(2, "zh", "旺财"));

                startActivity(i);
            }
        });
        System.out.println("onCreate");
    }

//B activity
private TextView tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_another_aty);

        Intent i = getIntent();  //直接获取传过来的intent
        tv = (TextView)findViewById(R.id.textView);
        //User u = (User)i.getSerializableExtra("user");
        User u = (User)i.getParcelableExtra("user");

        String s = String.format("测试21name=%s, age=%d 狗的名字=%s", u.getName(), u.getAge(), u.getDogName());
        tv.setText(s);
    }

简单总结（小白）： Serializable 比 Parcelable 使用起来方便，直接实现接口就好了，但是效率不高。  Parcelable效率高，但是需要自己写一些代码。