Intent使用详解

intent menu

Intent的使用方式

• 显示启动
• 隐式启动

显示Intent

 Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
 startActivity(intent);

隐式Intent

1.跳转到Activity

在清单文件中加入action，category

<activity android:name=".SecondActivity">
            <intent-filter>
                <action android:name="com.example.seele.activitytest.ACTION_START" />
                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="com.example.seele.activitytest.MY_CATEGORY" />
            </intent-filter>
</activity>

android.intent.category.DEFAULT 是默认的category

Intent intent = new Intent("com.example.seele.activitytest.ACTION_START");
        intent.addCategory("com.example.seele.activitytest.MY_CATEGORY");
        startActivity(intent);

2.跳转到网页

Intent intent = new Intent(Intent.ACTION_VIEW);
                intent.setData(Uri.parse("http://www.baidu.com"));
                startActivity(intent);

如果在清单文件中Activity加入action，catrgory，程序会让我们选择可以打开的界面（浏览器，ThirdActivity）

<activity android:name=".ThirdActivity">
            <intent-filter>
                <action android:name="android.intent.action.VIEW"/>
                <category android:name="android.intent.category.DEFAULT"/>
                <data android:scheme="http"/>
            </intent-filter>
        </activity>

3.跳转到拨号

Intent intent = new Intent(Intent.ACTION_DIAL);
                intent.setData(Uri.parse("tel:10086"));
                startActivity(intent);

4.Intent传递数据

//传递的activity
String data  = "Hello SecondActivity";
                Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
                intent.putExtra("extra_data",data);
                startActivity(intent);

//接收的activity
 Intent intent = getIntent();
        String data = getIntent().getStringExtra("extra_data");

5.返回给上一个活动数据

startActivityForResult传递的两个参数是 intent 和 请求码
onActivityResult传递的三个参数是requestCode（请求码） resultCode（处理结果） data（返回的数据）

FirstActivity
btn7.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
                startActivityForResult(intent,1);
            }
        });
 @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode){
            case 1:
                if(resultCode==RESULT_OK){
                    String returnedData = data.getStringExtra("data_return");
                    Toast.makeText(this,returnedData,Toast.LENGTH_SHORT).show();
                }
                break;
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

SecondActivity
@Override
    public void onBackPressed() {
        Intent intent = new Intent();
        intent.putExtra("data_return","Hello FirstActivity");
        setResult(RESULT_OK,intent);
        finish();
    }

在res目录新建一个menu文件夹，menu文件夹中新建main

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/add_item"
        android:title="Add"/>
    <item
        android:id="@+id/remove_item"
        android:title="Remove"/>
</menu>

在Activity中重写onCreateOptionsMenu和onOptionsItemSelected

public class FirstActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.first_layout);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main,menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()){
            case R.id.add_item:
                Toast.makeText(this,"You clicked Add",Toast.LENGTH_SHORT).show();
                break;
            case  R.id.remove_item:
                Toast.makeText(this,"You clicked Remove",Toast.LENGTH_SHORT).show();
                break;
        }
        return true;
    }
}

源码下载