Android--序列化数据存入、读出SD卡

序列化 内外存储写对象，需要写对象，在内存中传递对象，A activity 传入b activity中需要序列化。 序列化两种：serializable、Parcelable 支持可序列化： 对象读写文件推荐使用：serializable 在JAVA中建议使用Parcelable

例题：将数据传入SD卡中，启动就会读取 本题有两种方法：1.传入字符串：读取时根据分割字符读取 2.传入一个实体类 本题中使用第一种，在此给出第二种的方法

//传进去一个Object类 ok.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Message message=new Message(); message.setTitle(c1.isChecked()); message.setChajian(c3.isChecked()); message.setInformation(c2.isChecked()); message.setRead(c4.isChecked()); message.setCollection(c5.isChecked()); message.setCollection(c6.isChecked()); message.setSize(tv3.getText().toString()); String statu=Environment.getExternalStorageState(); if (!statu.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(SettingSDActivity.this,"SD卡未就绪",Toast.LENGTH_SHORT).show(); return ; } File root=Environment.getExternalStorageDirectory(); FileOutputStream fos=null; ObjectOutputStream oos=null; try { fos=new FileOutputStream(root+"/settings.txt"); try { oos=new ObjectOutputStream(fos); oos.writeObject(message); } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { e.printStackTrace(); }finally { if (fos != null) { try { fos.close(); fos.flush(); } catch (IOException e) { e.printStackTrace(); } } } } }); }

下面是实体对象的class文件 此处继承了Serializable 接口，实现序列化

public class Message implements Serializable { private Boolean title; private String size; private Boolean information; private Boolean chajian; private Boolean read; private Boolean collection; private Boolean top; public Message(Boolean title, String size, Boolean information, Boolean chajian, Boolean read, Boolean collection, Boolean top) { this.title = title; this.size = size; this.information = information; this.chajian = chajian; this.read = read; this.collection = collection; this.top = top; } public Boolean getTitle() { return title; } public void setTitle(Boolean title) { this.title = title; } public String getSize() { return size; } public void setSize(String size) { this.size = size; } public Boolean getInformation() { return information; } public void setInformation(Boolean information) { this.information = information; } public Boolean getChajian() { return chajian; } public void setChajian(Boolean chajian) { this.chajian = chajian; } public Boolean getRead() { return read; } public void setRead(Boolean read) { this.read = read; } public Boolean getCollection() { return collection; } public void setCollection(Boolean collection) { this.collection = collection; } public Boolean getTop() { return top; } public void setTop(Boolean top) { this.top = top; } public Message() { } }

下面为第一种方法代码：需要注意的是开始没有文件，会报错，需要加如判断。

public class SettingSDActivity extends AppCompatActivity { private CheckBox c1,c2,c3,c4,c5,c6; private TextView tv3,ok; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_setting_sd); c1=(CheckBox)findViewById(R.id.c1); c2=(CheckBox)findViewById(R.id.c2); c3=(CheckBox)findViewById(R.id.c3); c4=(CheckBox)findViewById(R.id.c4); c5=(CheckBox)findViewById(R.id.c5); c6=(CheckBox)findViewById(R.id.c6); tv3=(TextView)findViewById(R.id.tv3); ok=(TextView)findViewById(R.id.ok); tv3.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { AlertDialog.Builder builder=new AlertDialog.Builder(SettingSDActivity.this); builder.setTitle("字体大小请选择"); builder.setIcon(R.mipmap.ic_launcher); final String[] items={"大","中","小"}; // builder.setMultiChoiceItems()多选 builder.setSingleChoiceItems(items, 1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int i) { Toast.makeText(getBaseContext(), items[i].toString(), Toast.LENGTH_SHORT).show(); tv3.setText(items[i].toString()); dialog.dismiss(); } }); builder.setCancelable(false); AlertDialog alertDialog=builder.create(); alertDialog.show(); } }); ok.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { saveFile(); } }); //保存到SD卡上， public void saveFile(){ FileOutputStream fos=null; //获取SD卡状态 String state= Environment.getExternalStorageState(); //判断SD卡是否就绪 if(!state.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(this, "请检查SD卡", Toast.LENGTH_SHORT).show(); return; } //取得SD卡根目录 File file= Environment.getExternalStorageDirectory(); try { Log.d("=====SD卡根目录：", file.getCanonicalPath().toString()); //输出流的构造参数1：可以是File对象，也可以是文件路径 //输出流的构造参数2：默认为fasle=>覆盖内容：true=>追加内容 // File myFile=new File(file.getCanonicalPath()+"/sd.txt"); // fos=new FileOutputStream(myFile); //加true追加模式 //文件位置 fos=new FileOutputStream(file.getCanonicalPath()+"/sd.txt"); String str=content(); fos.write(str.getBytes()); Toast.makeText(this,"保存成功",Toast.LENGTH_SHORT).show(); } catch (IOException e) { e.printStackTrace(); }finally { if (fos!=null){ try { fos.close(); } catch (IOException e) { e.printStackTrace(); } } } } public String content(){ String a,b,c,d,e,f,g,h; if(c1.isChecked()){ a="check"; }else{ a="uncheck"; } if(c2.isChecked()){ b="check"; }else{ b="uncheck"; } if(c3.isChecked()){ c="check"; }else{ c="uncheck"; } if(c4.isChecked()){ d="check"; }else{ d="uncheck"; } if(c5.isChecked()){ e="check"; }else{ e="uncheck"; } if(c6.isChecked()){ f="check"; }else{ f="uncheck"; } g=tv3.getText().toString(); h=a+"#"+g+"#"+b+"#"+c+"#"+d+"#"+e+"#"+f; return h; } //读取文件 public String readFile(){ BufferedReader reader=null; FileInputStream fis=null; StringBuilder sbd=new StringBuilder(); String statu=Environment.getExternalStorageState(); if (!statu.equals(Environment.MEDIA_MOUNTED)){ Toast.makeText(this,"SD卡未就绪",Toast.LENGTH_SHORT).show(); return ""; } //拿到SD卡根目录 File root=Environment.getExternalStorageDirectory(); try { fis=new FileInputStream(root+"/sd.txt"); reader= new BufferedReader(new InputStreamReader(fis)); String row=""; try { while ((row=reader.readLine())!=null){ sbd.append(row); } } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { Toast.makeText(this,"文件不存在",Toast.LENGTH_SHORT).show(); e.printStackTrace(); }finally { if (reader!=null){ try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } return sbd.toString(); } //一开始就读取 @Override protected void onStart() { super.onStart(); String my = readFile(); if(my != ""){ String k[] = my.split("#"); if (k[0].equals("check")) { c1.setChecked(true); } else { c1.setChecked(false); } tv3.setText(k[1]); if (k[2].equals("check")) { c2.setChecked(true); } else { c2.setChecked(false); } if (k[3].equals("check")) { c3.setChecked(true); } else { c3.setChecked(false); } if (k[4].equals("check")) { c4.setChecked(true); } else { c4.setChecked(false); } if (k[5].equals("check")) { c5.setChecked(true); } else { c5.setChecked(false); } if (k[6].equals("check")) { c6.setChecked(true); } else { c6.setChecked(false); } } } }

接下来是布局文件

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal"> </LinearLayout> <ScrollView android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:layout_width="280dp" android:layout_height="wrap_content" android:text="设置" android:textSize="25sp" android:gravity="center" /> <TextView android:id="@+id/ok" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="提交" android:textSize="25sp" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="列表显示摘要" android:textSize="25sp" /> <CheckBox android:id="@+id/c1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textSize="25sp" android:layout_marginLeft="150dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" android:id="@+id/LL1" > <TextView android:id="@+id/tv2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="字体大小" android:textSize="25sp" /> <TextView android:id="@+id/tv3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="中 >" android:textSize="25sp" android:layout_marginLeft="205dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="列表页评论" android:textSize="25sp" /> <TextView android:id="@+id/tv5" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="不限 >" android:textSize="25sp" android:layout_marginLeft="153dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv6" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="2G/3G网络流量" android:textSize="25sp" /> <TextView android:id="@+id/tv7" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="较省流量（普通下载）>" android:textSize="15sp" android:layout_marginLeft="15dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv8" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="清理缓存" android:textSize="25sp" /> <TextView android:id="@+id/tv9" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="当前缓存：2.48MB>" android:textSize="20sp" android:layout_marginLeft="70dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv10" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="推送通知" android:textSize="25sp" /> <CheckBox android:id="@+id/c2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="200dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv11" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="互动插件" android:textSize="25sp" /> <CheckBox android:id="@+id/c3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="200dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv12" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="自动优化阅读" android:textSize="25sp" /> <CheckBox android:id="@+id/c4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="152dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv13" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="收藏时转发" android:textSize="25sp" /> <CheckBox android:id="@+id/c5" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="175dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_marginTop="10dp" android:layout_marginBottom="10dp" > <TextView android:id="@+id/tv14" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="顶踩时转发" android:textSize="25sp" /> <CheckBox android:id="@+id/c6" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="175dp" /> </LinearLayout> <View android:layout_width="match_parent" android:layout_height="1dp" android:background="#a9a8a8" ></View> </LinearLayout> </ScrollView> </LinearLayout>

实现效果如下：