android开发基础教程—文件存储功能实现

文件存储:

public class mainactivity extends activity {
edittext mname, mage;
textview mtv;
@override
protected void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.activity_main);
mname = (edittext) findviewbyid(r.id.edittext1);
mage = (edittext) findviewbyid(r.id.edittext2);
mtv = (textview) findviewbyid(r.id.textview1);
}
public void onclick(view v) {
string name = mname.gettext().tostring();
int age = integer.parseint(mage.gettext().tostring());
string cont = "name=" + name + ",age=" + age + "\n";
try {
int id = v.getid();
// 内部保存
if (id == r.id.button1) {
fileoutputstream fos = this.openfileoutput("mytext.txt",
context.mode_append | context.mode_world_writeable
| context.mode_world_readable);
fos.write(cont.getbytes());
fos.close();
toast.maketext(this, "写入完成", 1).show();
}
// 读取
else if (id == r.id.button2) {
fileinputstream fis = this.openfileinput("mytext.txt");
byte[] bytes = new byte[fis.available()];
fis.read(bytes);
fis.close();
string str = new string(bytes);
mtv.settext(str);
}
} catch (exception e) {
e.printstacktrace();
}
}

其他app如果想要访问这个mytext.txt文件格式如下:

public class mainactivity extends activity {
textview mcontent;
@override
protected void oncreate(bundle savedinstancestate) {
super.oncreate(savedinstancestate);
setcontentview(r.layout.activity_main);
mcontent=(textview) findviewbyid(r.id.textview1);
}
public void onclick(view v){
switch (v.getid()) {
case r.id.button1:
try {
readremotefilebyabslutepath();
} catch (exception e) {
// todo auto-generated catch block
e.printstacktrace();
}
break;
case r.id.button2:
try {
writeremotefilebyabslutepath();
} catch (exception e) {
// todo auto-generated catch block
e.printstacktrace();
}
break;
default:
break;
}
}
/**
* 通过文件绝对路径读取远程文件
* @throws exception
*/
public void readremotefilebyabslutepath() throws exception{
string path = "/data/data/com.nanguabing.filedemo/files/mytext.txt" ;
fileinputstream fis = new fileinputstream(path);
byte[] bytes = new byte[fis.available()];
fis.read(bytes);
fis.close();
string str = new string(bytes);
mcontent.settext(str);
log.i("other", str);
}
/**
* 通过文件绝对路径读取远程文件
* @throws exception
*/
public void writeremotefilebyabslutepath() throws exception{
string path = "/data/data/com.nanguabing.filedemo/files/mytext.txt" ;
fileoutputstream fos = new fileoutputstream(path,true);
fos.write("other write! ".getbytes());
fos.close();
log.i("other", "other write over!");
}
/**
* 通过包相关上下文写入远程文件
* @throws exception
*/
public void readromotebypackagecontext() throws exception {
string pname = "com.nanguabing.filedemo";
context ctx = this.createpackagecontext(pname,
context.context_ignore_security);
fileinputstream fis = ctx.openfileinput("mytext.txt");
byte[] bytes = new byte[fis.available()];
fis.read(bytes);
fis.close();
log.i("other",new string(bytes));
}
/**
* 通过包相关上下文写入远程文件
*/
public void readromotebypackagecontext2() throws exception {
string pname = "com.nanguabing.filedemo";
context ctx = this.createpackagecontext(pname,
context.context_include_code);
fileinputstream fis = ctx.openfileinput("mytext.txt");
byte[] bytes = new byte[fis.available()];
fis.read(bytes);
fis.close();
log.i("other",new string(bytes));
}
@override
public boolean oncreateoptionsmenu(menu menu) {
// inflate the menu; this adds items to the action bar if it is present.
getmenuinflater().inflate(r.menu.activity_main, menu);
return true;
}
}