安卓中操作文件读写

文件

通过文件流进行读写操作：FileInputStream , FileOutputStream 
对ROM中的files目录操作：String filePath = context.getFilesDir(); 
对ROM中的cache目录操作：String filePath = context.getCacheDir(); 
对SD卡目录操作：String filePath = Environment.getExternalStorageDirectory()

FileInputStream , FileOutputStream 和 
context.openFileOutput(“private.txt”,Context.MODE_PRIVATE); context.openFileInput(“private.txt”); 区别： 
FileInputStream , FileOutputStream可以指定任意路径下的文件进行读写； 
而openFileOutput ， openFileInput只能是ROM中当前应用名下files目录进行读写；

SharedPreferences

此方法是对ROM目录下的shared_prefs目录下的sp.xml文件进行读写操作

写入数据：

SharedPreferences sp = context.getSharedPreferences("sp",Context.MODE_PRIVATE);
Editor editor = sp.edit();
editor.putBoolean("gender", true);
editor.putString("username", username);
editor.putInt("age", 24);
editor.putFloat("salary", 13888.88f);
editor.commit();

取出数据：

SharedPreferences sp = this.getSharedPreferences("sp",
        Context.MODE_PRIVATE);
String username = sp.getString("username", "");
int age = sp.getInt("age", 0);
boolean gender = sp.getBoolean("gender", false);
float salary = sp.getFloat("salary", 0.0f);

xml(通过序列化的方式)

序列化

XmlSerializer serializer = Xml.newSerializer();
OutputStream os;
try {
    os = openFileOutput("provinces.xml", MODE_PRIVATE);
    serializer.setOutput(os, "utf-8");
    serializer.startDocument("utf-8", true);
    serializer.startTag(null, "provinces");

    serializer.startTag(null, "province");
    serializer.attribute(null, "pname", "浙江省");
    serializer.startTag(null, "city");
    serializer.text("杭州市");
    serializer.endTag(null, "city");
    serializer.startTag(null, "city");
    serializer.text("宁波市");
    serializer.endTag(null, "city");
    serializer.startTag(null, "city");
    serializer.text("温州市");
    serializer.endTag(null, "city");
    serializer.startTag(null, "city");
    serializer.text("台州市");
    serializer.endTag(null, "city");
    serializer.startTag(null, "city");
    serializer.text("绍兴市");
    serializer.endTag(null, "city");
    serializer.endTag(null, "province");

    serializer.startTag(null, "province");
    serializer.attribute(null, "pname", "湖北省");
    serializer.startTag(null, "city");
    serializer.text("武汉市");
    serializer.endTag(null, "city");
    serializer.startTag(null, "city");
    serializer.text("荆州市");
    serializer.endTag(null, "city");
    serializer.endTag(null, "province");

    serializer.endTag(null, "provinces");
    serializer.endDocument();

    os.close();
    Toast.makeText(this, "序列化成功", 0).show();
} catch (Exception e) {
    e.printStackTrace();
}

pull解析xml

XmlPullParser parser = Xml.newPullParser();
InputStream is = MainActivity.class.getClassLoader()
        .getResourceAsStream("provinces.xml");
try {
    parser.setInput(is, "utf-8");
    int type = parser.getEventType();
    List<Province> provinces = null;
    List<City> cities = null;
    Province p = null;
    City c = null;
    while (type != XmlPullParser.END_DOCUMENT) {
        String tagname = parser.getName();
        switch (type) {
        case XmlPullParser.START_TAG:
            if ("provinces".equals(tagname)) {
                provinces = new ArrayList<Province>();
            } else if ("province".equals(tagname)) {
                p = new Province();
                p.setPname(parser.getAttributeValue(0));
                cities = new ArrayList<City>();
                p.setCities(cities);
                provinces.add(p);
            } else if ("city".equals(tagname)) {
                c = new City();
                c.setCname(parser.nextText());
                cities.add(c);
            }
            break;

        default:
            break;
        }
        type = parser.next();
    }
    tv_info.setText(provinces.toString());
} catch (Exception e) {
    e.printStackTrace();
}

数据库

存储到数据库，不展开了。

服务器

可以把有些数据存储到服务器上，比如跟用户绑定的一些收藏，评论等数据