多个Activity跳转的小结

最新推荐文章于 2022-09-28 20:05:48 发布

最新推荐文章于 2022-09-28 20:05:48 发布 · 170 阅读

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#Android #JSP

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本文通过三个示例详细介绍了在Android开发中Activity之间的跳转方式，包括数据传递和回调机制。从简单的Main->SecondActivity->Main跳转到更复杂的Main->SecondActivity->ThirdActivity->Main和Main->SecondActivity->ThirdActivity->SecondActivity->Main，每个示例都展示了不同的跳转逻辑和返回参数处理方法。

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[color=red]转载请注明出处[/color]

在android开发中Activity相当于web开发的页面，或者说如j2ee开发中对应的jsp页面。在开发jsp时，经常会遇到页面跳转的问题，在android也同样会遇到。以下的几个例子是我对android的Activity跳转的小结，也是最近做项目的小结。

[size=large][color=red]第一个例子：demo1[/color][/size]
Main—>SecondActivity—>Main
从流程上看就是从Main跳转到SecondActivity，再从SecondActivity返回到Main。也就是将子Activity的数据返回给父Activity。
代码如下：

public class Main extends Activity {

	private Button btn;
	private TextView request_text;
	private final int FIRST_REQUEST_CODE = 1;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        request_text = (TextView)this.findViewById(R.id.request_text);

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent(Main.this,SecondActivity.class);
				i.putExtra("request_text_for_main", "从Main传递到SecondActivity");
				startActivityForResult(i, FIRST_REQUEST_CODE);
			}
		});
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	super.onActivityResult(requestCode, resultCode, data);
    	if(requestCode==FIRST_REQUEST_CODE && resultCode==Activity.RESULT_OK){
    		if(data != null) {
    			request_text.setText(data.getStringExtra("request"));
    		}
    	}
    }
}

public class SecondActivity extends Activity{

	private TextView request_text;
	private Button btn;
	private String text;

	public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);

        request_text = (TextView)this.findViewById(R.id.request_text);

        if (getIntent().getStringExtra("request_text_for_main") != null) {
        	text = getIntent().getStringExtra("request_text_for_main");
        	request_text.setText(text);
        }

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent();
				i.putExtra("request",text+"\n"+"从SecondActivity传递到ThirdActivity");
				setResult(Activity.RESULT_OK,i);
				finish();
			}
		});
	}
}

[img]http://dl.iteye.com/upload/attachment/332373/82b9aa9c-3029-3043-8884-a67caab7eeaa.png[/img]
图一

图一所示是demo初始化的样子，点击“第一次跳转”进入图二。

[img]http://dl.iteye.com/upload/attachment/332375/2d5dfb6a-d9ba-3891-8c53-fe7a1a2780ce.png[/img]
图二
图二显示从Main到SecondActivity这个过程，再点击“第二次跳转”即返回Main这个Activity。

[img]http://dl.iteye.com/upload/attachment/332377/eee750b1-cdb0-3423-8ce3-2e8554e1866f.png[/img]
图三
图三表示跳转结束，Button按钮上面的文字记录跳转的过程。

这个例子最主要是第一个Activity Main设置的onActivityResult()方法和startActivityForResult()方法。
在Main中通过startActivityForResult()调用SecondActivity，然后在onActivityResult()中获取其返回参数，或者说通过onActivityResult()进行回调。

SecondActivity中要返回第一个Main必须：
setResult(Activity.RESULT_OK,i);
finish();

[size=large][color=red]第二个例子：demo2[/color][/size]
Main—>SecondActivity—>ThirdActivity—>Main
这个例子的流程，比上一个更复杂一些，经历了3个Activity，最好跳转回第一个Activity。
代码如下：

public class Main extends Activity {

	private Button btn;
	private TextView request_text;
	private final int FIRST_REQUEST_CODE = 1;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        request_text = (TextView)this.findViewById(R.id.request_text);

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent(Main.this,SecondActivity.class);
				i.putExtra("request_text_for_main", "从Main传递到SecondActivity");
				startActivityForResult(i, FIRST_REQUEST_CODE);
			}
		});
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	super.onActivityResult(requestCode, resultCode, data);
    	if(requestCode==FIRST_REQUEST_CODE && resultCode==Activity.RESULT_FIRST_USER){
    		if(data != null) {
    			request_text.setText(data.getStringExtra("request_text_for_third"));
    		}
    	}
    }
}

public class SecondActivity extends Activity{

	private TextView request_text;
	private Button btn;
	private final int SECOND_REQUEST_CODE = 2;
	private String text;

	public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);

        request_text = (TextView)this.findViewById(R.id.request_text);

        if (getIntent().getStringExtra("request_text_for_main") != null) {
        	text = getIntent().getStringExtra("request_text_for_main");
        	request_text.setText(text);
        }

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent(SecondActivity.this,ThirdActivity.class);
				i.putExtra("request_text_for_second", text+"\n"+"从SecondActivity传递到ThirdActivity");
				startActivityForResult(i, SECOND_REQUEST_CODE);
			}
		});
	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {		
		super.onActivityResult(requestCode, resultCode, data);		
		if(requestCode==SECOND_REQUEST_CODE && data != null){
			setResult(Activity.RESULT_FIRST_USER, data);
			finish();
		}
	}
}

public class ThirdActivity extends Activity{

	private TextView request_text;
	private Button btn;
	private String text;

	public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.third);

        text = getIntent().getStringExtra("request_text_for_second");
        request_text = (TextView)this.findViewById(R.id.request_text);
        request_text.setText(text);

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent();
				i.putExtra("request_text_for_third", text+"\n"+"从ThirdActivity再次传递到Main");
				setResult(Activity.RESULT_FIRST_USER, i);
				finish();
			}
		});
	}

}

[img]http://dl.iteye.com/upload/attachment/332379/ce07e12d-7752-3bd3-82d9-2bdaf14e2f41.png[/img]

[img]http://dl.iteye.com/upload/attachment/332381/49a5bfeb-aac7-3ee7-872d-b67a994c7845.png[/img]

[img]http://dl.iteye.com/upload/attachment/332383/d0d42e31-3956-31dc-a4f2-3bae44f558cf.png[/img]

[img]http://dl.iteye.com/upload/attachment/332385/a23d3449-2022-3328-a79b-f564ff6e52f2.png[/img]

这个demo2比起前面的demo1的不同之处在于就是通过ThirdActivity进行跳转到Main。
在代码上的区别是：
(1)Main的onActivityResult()方法中,它的resultCode==Activity.RESULT_FIRST_USER而不是前面的resultCode==Activity.RESULT_OK
(2)SecondActivity中增加了onActivityResult()方法，该方法是用于回调ThirdActivity，并且该方法执行了跳转过程跳转到Main这个Activity。
(3) ThirdActivity和demo1的SecondActivity很类似。

[size=large][color=red]第三个例子：demo3[/color][/size]
Main—>SecondActivity—>ThirdActivity—>SecondActivity—>Main
这个过程看起来复杂，其实不然，最后一步是借助SecondActivity的另一个Button实现的。
代码如下：

public class Main extends Activity {
	private Button btn;
	private TextView request_text;
	private final int FIRST_REQUEST_CODE = 1;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        request_text = (TextView)this.findViewById(R.id.request_text);

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent(Main.this,SecondActivity.class);
				i.putExtra("request_text_for_main", "从Main传递到SecondActivity");
				startActivityForResult(i, FIRST_REQUEST_CODE);
			}
		});
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	super.onActivityResult(requestCode, resultCode, data);
    	if(requestCode==FIRST_REQUEST_CODE && resultCode==Activity.RESULT_FIRST_USER){
    		if(data != null) {
    			request_text.setText(data.getStringExtra("final_request"));
    		}
    	}
    }
}

public class SecondActivity extends Activity{

	private TextView request_text;
	private Button btn,finalBtn;
	private final int SECOND_REQUEST_CODE = 2;
	private String text;

	public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);

        request_text = (TextView)this.findViewById(R.id.request_text);

        if (getIntent().getStringExtra("request_text_for_main") != null) {
        	text = getIntent().getStringExtra("request_text_for_main");
        	request_text.setText(text);
        }

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent(SecondActivity.this,ThirdActivity.class);
				i.putExtra("request_text_for_second", text+"\n"+"从SecondActivity传递到ThirdActivity");
				startActivityForResult(i, SECOND_REQUEST_CODE);
			}
		});

        finalBtn = (Button)this.findViewById(R.id.finalBtn);
        finalBtn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent();
				i.putExtra("final_request", text+"\n"+"从SecondActivity最后传递到Main");
				setResult(Activity.RESULT_FIRST_USER,i);
				finish();
			}
		});
	}

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    	super.onActivityResult(requestCode, resultCode, data);
    	if(requestCode==SECOND_REQUEST_CODE && resultCode==Activity.RESULT_OK){
    		if(data != null) {
    			text = data.getStringExtra("request_text_for_third");
    			request_text.setText(text);
    		}
    	}
    }
}

public class ThirdActivity extends Activity{

	private TextView request_text;
	private Button btn;
	private String text;

	public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.third);

        text = getIntent().getStringExtra("request_text_for_second");
        request_text = (TextView)this.findViewById(R.id.request_text);
        request_text.setText(text);

        btn = (Button)this.findViewById(R.id.btn);
        btn.setOnClickListener(new OnClickListener() {
			public void onClick(View v) {
				Intent i = new Intent();
				i.putExtra("request_text_for_third", text+"\n"+"从ThirdActivity再次传递到SecondActivity");
				setResult(Activity.RESULT_OK, i);
				finish();
			}
		});
	}
}

[img]http://dl.iteye.com/upload/attachment/332387/213d9f40-f70f-342c-84e4-b641d64cc360.png[/img]

[img]http://dl.iteye.com/upload/attachment/332389/381db0ca-6e05-3cb9-8c12-dd7c501cda65.png[/img]

[img]http://dl.iteye.com/upload/attachment/332391/34b7f690-5aee-3aed-b109-f0021b84a45d.png[/img]

[img]http://dl.iteye.com/upload/attachment/332393/42a7da69-fcbd-309a-a798-f1e5a6dc0912.png[/img]

[img]http://dl.iteye.com/upload/attachment/332395/14ec6785-8c22-3bdf-89a2-5d608d13099b.png[/img]

比起前一个demo2其实没有更复杂之处，只是从ThirdActivity跳转回SecondActivity，而通过SecondActivity的另一个Button来跳转回Main的。