1. boolean contains(String key):判断SharedPreferences是否包含特定的key数据。
2. abstract Map<String,?> getAll():获取SharedPreferences数据里全部的ket-value对。
3. boolean getXxx(String key, xxx defValue):获取SharedPreferences数据里指定的key对应的value.如果key不存在，则返回默认值defValue.其中的xxx可以是boolean,float,int,long,String等各种基本类型的值。

1. SharedPreferences.Editor clear(): 清空SharedPreferences里所有数据。
2. ShraedPreferences.Editor putXxx(String key, Xxx value): 向SharedPreferences存入指定了key的数据value，value的类型可以是boolean,float,int,long,String等。
3. SharedPreferences.Editor remove(String key): 删除 Sharedpreferences里指定key对应的数据。
4. boolean commit(): 当Editor编辑完成后，调用该方法提交修改。

1. Context.MODE_PRIVATE: 指定该SharedPreferences数据只能被本应用读写。
2. Context.MODE_WORLD_READABLE: 指定该SharedPreferences数据能被其他应用程序读，但是不能写入。
3. Context.MODE_WORLD_WRITABLE: ShraedPreferences数据能被其他应用读写。

public class MainActivity extends Activity {


    private Button write;
    private Button read;
    private SharedPreferences preferences;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        write = (Button) findViewById(R.id.write);
        read = (Button) findViewById(R.id.read);


        preferences = getSharedPreferences("count",MODE_PRIVATE);


        //读取SharedsPreferences里的count数据
        int count = preferences.getInt("count",0);
        Toast.makeText(this,"程序以前被使用了" + count + "次。 ", Toast.LENGTH_LONG).show();


        //获取到SharedPreferences的editor，用来进行写入数据
        SharedPreferences.Editor editor = preferences.edit();


        //存入数据
        editor.putInt("count",++count);


        //提交修改
        editor.commit();
    }
}

Context context = createPackageContext("com.dada.example",Context.CONTEXT_IGNORE_SECURITY);

public class MainActivity extends ActionBarActivity {


    private Button write;
    private Button read;
    private int count;
    private SharedPreferences preferences;
    private SharedPreferences.Editor editor;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        write = (Button) findViewById(R.id.write);
        read = (Button) findViewById(R.id.read);


        Context myApplication = null;


        try{
            myApplication = createPackageContext("com.example.pc.myapplication",Context.CONTEXT_IGNORE_SECURITY);
            preferences = myApplication.getSharedPreferences("count",Context.MODE_WORLD_WRITEABLE);
            editor = preferences.edit();
        }
        catch (Exception e){
            e.printStackTrace();
        }






                write.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                editor.putInt("count",++count);


            }
        });


        read.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                count = preferences.getInt("count",0);
                Toast.makeText(getApplicationContext(),"count的值为" + count,Toast.LENGTH_LONG).show();


            }
        })；
    }
}