android_常用API

打电话, 文件读取与写入 ,共享偏好 ,手机中的html页面操纵


启动Android内置的拨号程序------------打电话啦

btnDial.setOnClickListener(new Button.OnClickListener(){//为按钮添加点击事件的监听器
			@Override
			public void onClick(View v) {//重写onClick方法
				Intent myIntent = new Intent(Intent.ACTION_DIAL);//创建Intent对象
				Sample_3_5.this.startActivity(myIntent);//启动Android内置的拨号程序
			}        	
        });

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文件读取与写入

FileOutputStream fout = openFileOutput(fileName, MODE_PRIVATE);//获得FileOutputStream对象

FileInputStream fin = openFileInput(fileName);//获得FileInputStream对象

openFileOutput()方法的第一参数用于指定文件名称，不能包含路径分隔符“/” ，如果文件不存在，Android 会自动创建它。创建的文件保存在/data/data/<package name>/files目录，如： /data/data/cn.itcast.action/files/itcast.txt
如果希望文件被其他应用读和写，可以传入： 
openFileOutput("itcast.txt", Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE);
Activity还提供了getCacheDir()和getFilesDir()方法：
getCacheDir()方法用于获取/data/data/<package name>/cache目录
getFilesDir()方法用于获取/data/data/<package name>/files目录

在程序中访问SDCard，你需要申请访问SDCard的权限。
在AndroidManifest.xml中加入访问SDCard的权限如下:
<!-- 在SDCard中创建与删除文件权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!-- 往SDCard写入数据权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
         File sdCardDir = Environment.getExternalStorageDirectory();//获取SDCard目录
         File saveFile = new File(sdCardDir, “itcast.txt”);
FileOutputStream outStream = new FileOutputStream(saveFile);
outStream.write("传智播客".getBytes());
outStream.close();
}



InputStream in = getResources().openRawResource(R.raw.test1);	//从Resources中raw中的文件获取输入流

InputStream in = getResources().getAssets().open(fileName);		//从Assets中的文件获取输入流

EncodingUtils.getString(buffer, ENCODING);	

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public class DatabaseHelper extends SQLiteOpenHelper {
    //类没有实例化,是不能用作父类构造器的参数,必须声明为静态
         private static final String name = "itcast"; //数据库名称
         private static final int version = 1; //数据库版本
         public DatabaseHelper(Context context) {
//第三个参数CursorFactory指定在执行查询时获得一个游标实例的工厂类,设置为null,代表使用系统默认的工厂类
                super(context, name, null, version);
         }
        @Override public void onCreate(SQLiteDatabase db) {
              db.execSQL("CREATE TABLE IF NOT EXISTS person (personid integer primary key autoincrement, name varchar(20), age INTEGER)");   
         }
        @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
               db.execSQL("DROP TABLE IF EXISTS person");
               onCreate(db);
         }
}
DatabaseHelper databaseHelper = new DatabaseHelper(HelloActivity.this);
		SQLiteDatabase db = databaseHelper.getWritableDatabase();
		db.execSQL("insert into person(name, age) values(?,?)", new Object[]{"传智播客", 4});	
		db.close();  

db.beginTransaction();//开始事务
try {
    db.execSQL("insert into person(name, age) values(?,?)", new Object[]{"传智播客", 4});
    db.execSQL("update person set name=? where personid=?", new Object[]{"传智", 1});
    db.setTransactionSuccessful();//调用此方法会在执行到endTransaction() 时提交当前事务，如果不调用此方法会回滚事务
} finally {
    db.endTransaction();//由事务的标志决定是提交事务，还是回滚事务
} 
db.close(); 

---------
Cursor cursor = db.rawQuery(“select * from person”, null);
while (cursor.moveToNext()) {
	int personid = cursor.getInt(0); //获取第一列的值,第一列的索引从0开始
	String name = cursor.getString(1);//获取第二列的值
	int age = cursor.getInt(2);//获取第三列的值
}
cursor.close();
db.close(); 

或者：
int nameIndex = cursor.getColumnIndex("name");	//获取name列的索引
		int levelIndex = cursor.getColumnIndex("level");	//获取level列的索引
		for(cursor.moveToFirst();!(cursor.isAfterLast());cursor.moveToNext()){	//遍历查询结果集，将数据提取出来
			result = result + cursor.getString(nameIndex)+"    ";
			result = result + cursor.getInt(levelIndex)+"     \n";
		}

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共享偏好对象---相当于java中的properties ,就是键值对

 sp = getPreferences(MODE_PRIVATE);		//获得SharedPreferences对象
        String result = sp.getString(EDIT_TEXT_KEY, null);
        if(result != null){		//如果获取的值不为空
        	etPre.setText(result);	//EditText对象显示的内容设置为读取的数据
        }


SharedPreferences.Editor editor = sp.edit();	//获得SharedPreferences的Editor对象
		editor.putString(EDIT_TEXT_KEY, String.valueOf(etPre.getText()));	//修改数据
		editor.commit();			//必须调用该方法以提交修改

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手机中的html页面操纵
普通的带js的html页面

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<script type="text/javascript">
	function contactlist(jsons){
		var table = document.getElementById("contactTable");
		var arr = eval(jsons);
		for(var i=0;i<arr.length;i++){
			var jsonObj = arr[i];
			var tr = table.insertRow(table.rows.length);
			var td1 = tr.insertCell(0);
			var td2 = tr.insertCell(1);
			td2.align = "center";
			var td3 = tr.insertCell(2);
			
			td1.innerHTML = jsonObj.id;
			td2.innerHTML = jsonObj.name;
			td3.innerHTML = "<a href=\"javascript:webHandler.call('"+jsonObj.phone+"')\">"+jsonObj.phone+"</a>";
		}
	}
	
	function pageInit(){
		var content = "[{id:56,name:'老张',phone:'123456789'},{id:12,name:'老比',phone:'5556'}]";
		
		contactlist(content);
		
	}
</script>
<body onload="pageInit()">
<table width="100%" border="0" cellspacing="0" id="contactTable">
	<tr bgcolor="#EEF7FF" style="font-size:18px;font-weight:bold;">
		<td width="20%">编号</td>
		<td align="center">姓名</td>
		<td width="30%">电话</td>
	</tr>
</table>

</body>
</html>

main.xml中有专门的webView来弄xml

 <WebView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/webView" />

private Handler handler = new Handler();
webview = (WebView)this.findViewById(R.id.webView);
        webview.getSettings().setJavaScriptEnabled(true);
        webview.getSettings().setSupportZoom(false);//设置缩放
        webview.getSettings().setAppCacheEnabled(false);
        webview.getSettings().setAllowFileAccess(true);
        webview.addJavascriptInterface(new JSHandler(this,handler), "webHandler");
        String url = "file:///android_asset/index.html";
        webview.loadUrl(url);

处理js的类

public class JSHandler {

	private Context context;
	private WebView webView;
	private Handler handler;
	
	public JSHandler(Context context,Handler handler){
		this.context = context;
		this.handler = handler;
		webView = (WebView)((Activity)context).findViewById(R.id.webView);
		
	}
	//在java中调用js的方法，并往js传递数据
	public void show(){
		handler.post(new Runnable() {
			@Override
			public void run() {
				webView.loadUrl("javascript:contactlist('"+query()+"')");
			}
		});
	}
	
	public void call(final String phone){
		handler.post(new Runnable() {
			@Override
			public void run() {
				Toast.makeText(context, "hhh", 0).show();
				context.startActivity(new Intent(Intent.ACTION_CALL,Uri.parse("tel:"+phone)));
			}
		});
		
	}
	
	public String query(){
		JSONObject jsonObject = new JSONObject();
		JSONObject jsonObject2 = new JSONObject();
		JSONArray arr = new JSONArray();
		try {
			jsonObject.put("id", 56);
			jsonObject.put("name", "老张");
			jsonObject.put("phone", "5556");
			
			jsonObject2.put("id", 89);
			jsonObject2.put("name", "老放");
			jsonObject2.put("phone", "5558");
			
			arr.put(jsonObject);
			arr.put(jsonObject2);
		} catch (JSONException e) {
		}
		return arr.toString();
	}
}

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