Activity开发要点合集

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1.serResult

package cn.itcast.getdata;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.widget.EditText;public class DemoActivity extends Activity {EditText et, et2;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);et = (EditText) this.findViewById(R.id.et_contact1);et2 = (EditText) this.findViewById(R.id.et_contact2);}public void click(View view) {Intent intent = new Intent(this, ContactActivity.class);// startActivity(intent);startActivityForResult(intent, 1);}public void click2(View view) {Intent intent = new Intent(this, ContactActivity.class);// startActivity(intent);startActivityForResult(intent, 2);}/** * 当被激活的activity 使用完毕 销毁的时候 就会执行onActivityresult的方法 */@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {// TODO Auto-generated method stubSystem.out.println("结果码为"+ resultCode);super.onActivityResult(requestCode, resultCode, data);if (data != null) {String name = data.getStringExtra("name");if (requestCode == 1) {et.setText(name);}else if(requestCode == 2){et2.setText(name);}}}}

package cn.itcast.getdata;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.content.Intent;import android.database.Cursor;import android.graphics.Color;import android.net.Uri;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;aimport android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.BaseAdapter;import android.widget.ListView;import android.widget.TextView;public class ContactActivity extends Activity {ListView lv;List<String> names;@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);setContentView(R.layout.contact);lv = (ListView) this.findViewById(R.id.lv);names = getContacts();lv.setAdapter(new MyAdapter());lv.setOnItemClickListener(new OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> parent, View view,int position, long id) {TextView tv = (TextView) view;String name = tv.getText().toString();Intent data = new Intent();data.putExtra("name", name);setResult(3, data);// 可以把当前的activity给结束掉 finish();}});}private class MyAdapter extends BaseAdapter{@Overridepublic int getCount() {// TODO Auto-generated method stubreturn names.size();}@Overridepublic Object getItem(int position) {// TODO Auto-generated method stubreturn position;}@Overridepublic long getItemId(int position) {// TODO Auto-generated method stubreturn position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {TextView tv = new TextView(ContactActivity.this);tv.setTextSize(28);tv.setTextColor(Color.RED);tv.setText(names.get(position));return tv;}}private List<String> getContacts (){String rawbase = "content://com.android.contacts/raw_contacts";String database = "content://com.android.contacts/data";Cursor cursor = this.getContentResolver().query(Uri.parse(rawbase), null, null, null, null);List<String> names = new ArrayList<String>();while (cursor.moveToNext()) {String id  = cursor.getString( cursor.getColumnIndex("_id"));System.out.println("id ="+ id);Cursor datacursor = this.getContentResolver().query(Uri.parse(database), null, "raw_contact_id=?", new String[]{id}, null);while (datacursor.moveToNext()) {String type = datacursor.getString(datacursor.getColumnIndex("mimetype"));if("vnd.android.cursor.item/name".equals(type)){String data1 = datacursor.getString( datacursor.getColumnIndex("data1"));names.add(data1);}}datacursor.close();}cursor.close();return names;}}

2.跳转Activity

package cn.itcast.mutileactivity;import android.app.Activity;import android.content.ComponentName;import android.content.Intent;import android.net.Uri;import android.os.Bundle;import android.view.View;public class Demo1Activity extends Activity {    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);    }            public void open(View view){    // intent 意图 , 描述一个动作, 激活一个组件     /*第一种写法      * Intent intent = new Intent();    intent.setClassName("cn.itcast.mutileactivity", "cn.itcast.mutileactivity.Demo2Activity");*/     // 第二种写法      //Intent intent = new Intent(this,Demo2Activity.class);        /*         *第三种写法     Intent intent = new Intent();    ComponentName  component = new ComponentName("cn.itcast.mutileactivity", "cn.itcast.mutileactivity.Demo2Activity");    intent.setComponent(component);    */    //前面的三种写法 要求必须要知道 被激活的组件的包名和 class的名字     //显示意图     //****************************************************//    Intent intent = new Intent();//    intent.setAction("cn.itcast.mutileactivity.xxx");//    intent.addCategory("android.xxx");//    intent.setData(Uri.parse("itcast://cn.itcast.demo"));    //intent.setType(type);  // mime 数据类型 image/jpeg    // 隐式意图     // 只需要指定 intent的动作 ,intent的数据      // 如果我们想激活另外一个应用程序的组件 //    Intent intent = new Intent();//    intent.setAction(Intent.ACTION_PICK);//    //    intent.setType("image/jpeg");        // intent 要去做一件事  泡 动作 泡茶 泡咖啡 泡妞 打人  打酱油     // intent.setData();指定数据的类型 type     // intent.addCategory();    /**     *    <intent-filter>                <action android:name="android.intent.action.VIEW" />                <category android:name="android.intent.category.DEFAULT" />                <data android:mimeType="vnd.android-dir/mms-sms" />            </intent-filter>     *//*    Intent intent = new Intent();    intent.setAction(Intent.ACTION_VIEW);    intent.addCategory("android.intent.category.DEFAULT");    intent.setType("vnd.android-dir/mms-sms");*/    /**     *             <intent-filter>                <action android:name="android.intent.action.VIEW" />                <action android:name="android.intent.action.SENDTO" />                <category android:name="android.intent.category.DEFAULT" />                <category android:name="android.intent.category.BROWSABLE" />                <data android:scheme="sms" />                <data android:scheme="smsto" />            </intent-filter>     */        Intent intent = new Intent();    intent.setAction("android.intent.action.SENDTO");    intent.addCategory("android.intent.category.DEFAULT");    intent.setData(Uri.parse("smsto:123456"));    startActivity(intent);    }}

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="cn.itcast.mutileactivity"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk android:minSdkVersion="8" />    <application        android:icon="@drawable/ic_launcher"        android:label="@string/app_name" >        <activity            android:label="@string/app_name"            android:name=".Demo1Activity" >            <intent-filter >                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>        <activity            android:label="@string/activity02"            android:name=".Demo2Activity" ><intent-filter >                <action android:name="cn.itcast.mutileactivity.Demo2Activity" />                <action android:name="cn.itcast.mutileactivity.xxx" />                <category android:name="android.intent.category.DEFAULT" />                <category android:name="android.xxx" />            </intent-filter>        </activity>    </application></manifest>

3.onSaveInstance的使用

package cn.itcast.life;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;/** * 什么是生命周期   一个对象 从被创建出来new() 到 被销毁 (垃圾回收)这个过程当前必须执行的方法  *  * @author zehua * */public class DemoActivity extends Activity {public void click(View view){Intent intent = new Intent(this,Dmeo2Activity.class);startActivity(intent);}/** * activity第一次被创建的时候 执行的方法 */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        int page = 0;        //pdf 阅读器  当前用户读到了第30页         if(savedInstanceState!=null){        page = savedInstanceState.getInt("page");        System.out.println("定位到 第 "+ page+"页");        }                System.out.println("oncreate");    }                /**     * 在activity被异常 回收的时候 会被执行      */    @Overrideprotected void onSaveInstanceState(Bundle outState) {super.onSaveInstanceState(outState);outState.putInt("page", 30);}/**     * 用户可见的时候 调用onstart();     */@Overrideprotected void onStart() {// TODO Auto-generated method stubsuper.onStart();        System.out.println("onStart");       // System.out.println("判断是否有暂停的位置 ,从暂停的位置继续播放");}@Overrideprotected void onRestart() {// TODO Auto-generated method stubsuper.onRestart();        System.out.println("onRestart");}@Overrideprotected void onResume() {// TODO Auto-generated method stubsuper.onResume();        System.out.println("onResume");}@Overrideprotected void onPause() {// TODO Auto-generated method stubsuper.onPause();        System.out.println("onPause");}@Overrideprotected void onStop() {// TODO Auto-generated method stub//System.out.println("暂停视频播放");super.onStop();     System.out.println("onStop");}/** * activity 被销毁的时候 执行的方法  */@Overrideprotected void onDestroy() {// TODO Auto-generated method stubsuper.onDestroy();        System.out.println("onDestroy");}    }