初学Android:意图之intent

时间:2024-09-14 23:33:56

Intent意为:意图。简单的理解就是用来从一个Activity/Service跳转到另一个Activity/Service中,并可以携带数据,也可以在这个程序调用别的程序。这样我们虽然不懂如何结息条形码,却可以通过开放的android平台,在我们的程序调用专家写好的程序来实现功能。

Intent的用法:

(1)从MainActivity不携带数据跳转到NewActivity

Intent intent=new Intent(MainActivity,this,NewActivity.this);

startAcitivity(intent);

(2)从MainActivity携带数据跳转到NewActivity,

Intent intent=new Intent(MainActivity,this,NewActivity.this);

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Bundle bundle=new Bundle();

bundle.putString("name", "value");

intent.putExtras(bundle);//注意有加S,bundle可以放入多组值要与intent.putExtra()进行区别

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intent.putExtra("name","value");

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startAcitivity(intent);

接收

mintent=this.getIntent();//注意点!用this.getIntent()而不是new出来的

String a=mintent.getStringExtra("name");

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第一种方法当bundle的值要传给多个activity时较为简便。

(3)从MainActivity跳转到NewActivity,并携带数据,并且要从NewActivity跳转回MainActivity且携带数据。

Intent intent=new Intent(MainActivity.this,NewActivity.class);
Bundle bundle=new Bundle();
bundle.putString("name","value");
intent.putExtras(bundle);
startActivityForResult(intent,1234);

protected void onActivityResult(int requestCode,int resultCode,Intent data)
{
  if (resultCode==4321)
  {
    String a=data.getStringExtra("name");
    Toast.makeText(this, a, Toast.LENGTH_LONG).show();;
  }
  super.onActivityResult(requestCode, resultCode, data);
}

//请求码requestCode=1234

Intent mintent=new Intent(this,MainActivity);

mintent.putExtra("name", "你好");
setResult(4321, mintent);//4321为结果码
finish();

//程序例子A调用程序例子B

intent.setClassName("com.example.lizib", "com.example.lizib.MainActivity");
Bundle bundle=new Bundle();
bundle.putString("STR_INPUT", "HI,我来自例子A...");
intent.putExtras(bundle);
startActivityForResult(intent, 1234);

protected void onActivityResult(int requestCode,int resultCode,Intent data)
{
if (resultCode!=RESULT_OK)
{
return;
}
else
{
String aaa=data.getStringExtra("STR_BACK");
tv.setText("来自例子B:"+aaa);
}
super.onActivityResult(requestCode, resultCode, data);
}

//接收

Bundle bundle=getIntent().getExtras();
strRet=bundle.getString("STR_INPUT");

//返回

Bundle bundle=new Bundle();
bundle.putString("STR_BACK", "我是例子B");
Intent intent=new Intent();
intent.putExtras(bundle);
setResult(RESULT_OK,intent);
finish();