- Android五种数据传递方法汇总
- Android开发中，在不同模块(如Activity)间经常会有各种各样的数据需要相互传递，我把常用的几种 方法都收集到了一起。它们各有利弊，有各自的应用场景。我现在把它们集中到一个例子中展示,在例子中每一个按纽代表了一种实现方法。
1. 利用Intent对象携带简单数据利用Intent的Extra部分来存储我们想要传递的数据，可以传送int, long, char等一些基础类型,对复杂的对象就无能为力了。1.1 设置参数[java]//传递些简单的参数Intent intentSimple = new Intent();intentSimple.setClass(MainActivity.this,SimpleActivity.class);Bundle bundleSimple = new Bundle();bundleSimple.putString("usr", "xcl");bundleSimple.putString("pwd", "zj");intentSimple.putExtras(bundleSimple);startActivity(intentSimple);1.2 接收参数[java]this.setTitle("简单的参数传递例子");//接收参数Bundle bunde = this.getIntent().getExtras();String eml = bunde.getString("usr");String pwd = bunde.getString("pwd");2. 利用Intent对象携带如ArrayList之类复杂些的数据这种原理是和上面一种是一样的，只是要注意下。 在传参数前，要用新增加一个List将对象包起来。2.1 设置参数[java]//传递复杂些的参数Map<String, Object> map1 = new HashMap<String, Object>();map1.put("key1", "value1");map1.put("key2", "value2");List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();list.add(map1);Intent intent = new Intent();intent.setClass(MainActivity.this,ComplexActivity.class);Bundle bundle = new Bundle();//须定义一个list用于在budnle中传递需要传递的ArrayList<Object>,这个是必须要的ArrayList bundlelist = new ArrayList();bundlelist.add(list);bundle.putParcelableArrayList("list",bundlelist);intent.putExtras(bundle);startActivity(intent);2.1 接收参数[java]<span style="white-space:pre"> </span> this.setTitle("复杂参数传递例子");//接收参数Bundle bundle = getIntent().getExtras();ArrayList list = bundle.getParcelableArrayList("list");//从List中将参数转回 List<Map<String, Object>>List<Map<String, Object>> lists= (List<Map<String, Object>>)list.get(0);String sResult = "";for (Map<String, Object> m : lists){for (String k : m.keySet()){sResult += "\r\n"+k + " : " + m.get(k);}}3. 通过实现Serializable接口3.1 设置参数利用Java语言本身的特性，通过将数据序列化后，再将其传递出去。[java]//通过Serializable接口传参数的例子HashMap<String,String> map2 = new HashMap<String,String>();map2.put("key1", "value1");map2.put("key2", "value2");Bundle bundleSerializable = new Bundle();bundleSerializable.putSerializable("serializable", map2);Intent intentSerializable = new Intent();intentSerializable.putExtras(bundleSerializable);intentSerializable.setClass(MainActivity.this,SerializableActivity.class);startActivity(intentSerializable);3.2 接收参数[java]this.setTitle("Serializable例子");//接收参数Bundle bundle = this.getIntent().getExtras();//如果传 LinkedHashMap，则bundle.getSerializable转换时会报ClassCastException，不知道什么原因//传HashMap倒没有问题。HashMap<String,String> map = (HashMap<String,String>)bundle.getSerializable("serializable");String sResult = "map.size() ="+map.size();Iterator iter = map.entrySet().iterator();while(iter.hasNext()){Map.Entry entry = (Map.Entry)iter.next();Object key = entry.getKey();Object value = entry.getValue();sResult +="\r\n key----> "+(String)key;sResult +="\r\n value----> "+(String)value;}4. 通过实现Parcelable接口这个是通过实现Parcelable接口，把要传的数据打包在里面，然后在接收端自己分解出来。这个是Android独有的，在其本身的 中也用得很多，效率要比Serializable相对要好。4.1 首先要定义一个类，用于 实现Parcelable接口因为其本质也是序列化数据，所以这里要注意定义顺序要与解析顺序要一致噢。[java]public class XclParcelable implements Parcelable {//定义要被传输的数据public int mInt;public String mStr;public HashMap<String,String> mMap = new HashMap<String,String>();//Describe the kinds of special objects contained in this Parcelable's marshalled representation.public int describeContents() {return 0;}//Flatten this object in to a Parcel.public void writeToParcel(Parcel out, int flags) {//等于将数据映射到Parcel中去out.writeInt(mInt);out.writeString(mStr);out.writeMap(mMap);}//Interface that must be implemented and provided as a public CREATOR field//that generates instances of your Parcelable class from a Parcel.public static final Parcelable.Creator<XclParcelable> CREATOR= new Parcelable.Creator<XclParcelable>() {public XclParcelable createFromParcel(Parcel in) {return new XclParcelable(in);}public XclParcelable[] newArray(int size) {return new XclParcelable[size];}};private XclParcelable(Parcel in) {//将映射在Parcel对象中的数据还原回来//警告，这里顺序一定要和writeToParcel中定义的顺序一致才行!!!mInt = in.readInt();mStr = in.readString();mMap = in.readHashMap(HashMap.class.getClassLoader());}public XclParcelable() {// TODO Auto-generated constructor stub}}4.2 设置参数[java]//通过实现Parcelable接口传参的例子Intent intentParcelable = new Intent();XclParcelable xp = new XclParcelable();xp.mInt = 1;xp.mStr = "字符串";xp.mMap = new HashMap<String,String>();xp.mMap.put("key", "value");intentParcelable.putExtra("Parcelable", xp);intentParcelable.setClass(MainActivity.this,ParcelableActivity.class);startActivity(intentParcelable);4.3 接收参数[java]<span style="white-space:pre"> </span>this.setTitle("Parcelable例子");//接收参数Intent i = getIntent();XclParcelable xp = i.getParcelableExtra("Parcelable");TextView tv = (TextView)findViewById(R.id.tv);tv.setText( " mInt ="+xp.mInt+"\r\n mStr"+xp.mStr+"\r\n size()="+xp.mMap.size());5. 通过单例模式实现参数传递单例模式的特点就是可以保证 中一个类有且只有一个实例。这样很容易就能实现，在A中设置参数，在B中直接访问了。这是几种方法中效率最高的。5.1 定义一个单实例的类[java]//单例模式public class XclSingleton{//单例模式实例private static XclSingleton instance = null;//synchronized 用于线程安全，防止多线程同时创建实例public synchronized static XclSingleton getInstance(){if(instance == null){instance = new XclSingleton();}return instance;}final HashMap<String, Object> mMap;public XclSingleton(){mMap = new HashMap<String,Object>();}public void put(String key,Object value){mMap.put(key,value);}public Object get(String key){return mMap.get(key);}}5.2 设置参数[java]//通过单例模式传参数的例子XclSingleton.getInstance().put("key1", "value1");XclSingleton.getInstance().put("key2", "value2");Intent intentSingleton = new Intent();intentSingleton.setClass(MainActivity.this,SingletonActivity.class);startActivity(intentSingleton);5.3 接收参数[java]<span style="white-space:pre"> </span>this.setTitle("单例模式例子");//接收参数HashMap<String,Object> map = XclSingleton.getInstance().mMap;String sResult = "map.size() ="+map.size();//遍历参数Iterator iter = map.entrySet().iterator();while(iter.hasNext()){Map.Entry entry = (Map.Entry)iter.next();Object key = entry.getKey();Object value = entry.getValue();sResult +="\r\n key----> "+(String)key;sResult +="\r\n value----> "+(String)value;}