android-day2- save read file, xml , sqlite basic function

今天的主要内容是  分别用普通方式和SharedPreferences读取文件，xml 解析和生成，sqlite的增删改查。获取sd卡的大小

1 用普通方式存储和读取qq的用户名和密码
存
fos = context.openFileOutput("password.txt", Context.MODE_WORLD_READABLE);
String content = account + ":" + password;
fos.write(content.getBytes());
读
FileInputStream fis = this.openFileInput("password.txt");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len=0;
while((len=fis.read(buffer))>0){
baos.write(buffer, 0, len);
}
String str = baos.toString();
String[] input = str.split(":");
Log.i(tag, input[0]);
Log.i(tag, input[1]);
account.setText(input[0]);
password.setText(input[1]);
2 用SharedPreferences 存取文件
存
SharedPreferences sp = context.getSharedPreferences("config.txt", Context.MODE_WORLD_READABLE|Context.MODE_WORLD_WRITEABLE);
Editor editor = sp.edit();
editor.putString("account", account);
editor.putString("password", password);
editor.commit();
取
3 xml 解析和生成
解析
public List<Person> parseXml() {
List<Person> list = new ArrayList<Person>();
Person p = null;
AssetManager manager = context.getAssets();
InputStream in = null;
try {
in = manager.open("person.xml");
XmlPullParser parser = Xml.newPullParser();
parser.setInput(in, "utf-8");
int eventType = parser.getEventType();
while(eventType!=XmlPullParser.END_DOCUMENT){
if(eventType==XmlPullParser.START_TAG){
if("person".equals(parser.getName())){
p = new Person();
int id = Integer.parseInt(parser.getAttributeValue(0));
p.setId(id);
}else if("name".equals(parser.getName())){
String name = parser.nextText();
p.setName(name);
}else if("age".equals(parser.getName())){
int age = Integer.parseInt(parser.nextText());
p.setAge(age);
}
}
if(eventType==XmlPullParser.END_TAG){
if("person".equals(parser.getName())){
list.add(p);
}
}
eventType = parser.next();
}

生成
public boolean saveToXml(List<Person> list){
XmlSerializer serializer = Xml.newSerializer();
try {
File file = new File(Environment.getExternalStorageDirectory(),"persons.xml");
FileOutputStream fos = new FileOutputStream(file);
serializer.setOutput(fos, "utf-8");
serializer.startDocument("utf-8", true);
serializer.startTag(null, "persons");
for(Person person:list){
serializer.startTag(null, "person");
serializer.attribute(null, "id", person.getId()+"");

serializer.startTag(null, "name");
serializer.text(person.getName());
serializer.endTag(null, "name");


serializer.startTag(null, "age");
serializer.text(person.getAge()+"");
serializer.endTag(null, "age");

serializer.endTag(null,"person");
}
4sqlite的增删改查
首先自己定义一个继承于SQLiteOpenHelper的类用来创建数据库和表
public class MySqliteOpenHelper extends SQLiteOpenHelper {

public MySqliteOpenHelper(Context context) {
super(context, "itheima.db", null, 3);

}
public void onCreate(SQLiteDatabase db) {
System.out.println("create table");
db.execSQL("CREATE TABLE person (personid integer primary key autoincrement, name varchar(20),phone varchar(20))");
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
接着在dao的构造函数里初始化MySqliteOpenHelper
public PersonDao(Context context){
myHelper = new MySqliteOpenHelper(context);
}
最后就是增删改查
public boolean addPerson(Person person){
String name = person.getName();
String phone =  person.getPhone();
SQLiteDatabase db = myHelper.getWritableDatabase();
if(db.isOpen()){
db.execSQL("insert into person values(null,?,?)", new String[]{name,phone});
db.close();
return true;
}
return false;
}

public boolean deletePersonByName(String name){
SQLiteDatabase db = myHelper.getWritableDatabase();
if(db.isOpen()){
db.execSQL("delete from person where name=?", new String[]{name});
db.close();
return true;
}
return false;
}

public boolean update(Person person){
SQLiteDatabase db = myHelper.getWritableDatabase();

System.out.println(person.getName() + "::"+person.getPhone() + "::"+person.getId());
if(db.isOpen()){
db.execSQL("update person set name=? , phone=? where personid=?", new String[]{person.getName(),person.getPhone(),person.getId()+""});
db.close();
return true;
}
return false;
}

public Person findPersonByName(String name){
SQLiteDatabase db = myHelper.getReadableDatabase();
if(db.isOpen()){
Cursor cursor = db.rawQuery("select * from person where name=?", new String[]{name});
if(cursor.moveToFirst()){

int indexid = cursor.getColumnIndex("personid");
String personid = cursor.getString(indexid);
int indexName = cursor.getColumnIndex("name");
String personName = cursor.getString(indexName);
int indexPhone = cursor.getColumnIndex("phone");
String phoneNo = cursor.getString(indexPhone);
Person person = new Person();
person.setId(Integer.parseInt(personid));
person.setName(personName);
person.setPhone(phoneNo);
return person;
}
}
return null;
}
public List<Person> findAllPerson(){
List<Person> persons = new ArrayList<Person>();
SQLiteDatabase db = myHelper.getReadableDatabase();
if(db.isOpen()){
Cursor cursor = db.rawQuery("select * from person", null);
while(cursor.moveToNext()){
int indexid = cursor.getColumnIndex("personid");
String personid = cursor.getString(indexid);
int indexName = cursor.getColumnIndex("name");
String personName = cursor.getString(indexName);
int indexPhone = cursor.getColumnIndex("phone");
String phoneNo = cursor.getString(indexPhone);
Person person = new Person();
person.setId(Integer.parseInt(personid));
person.setName(personName);
person.setPhone(phoneNo);
persons.add(person);
}
}
return persons;
}

5 获取sd卡的大小
File path = Environment.getExternalStorageDirectory();
        StatFs stat = new StatFs(path.getPath());
        long blockSize = stat.getBlockSize();
        long totalBlocks = stat.getBlockCount();
        long totalbytes =  blockSize*totalBlocks;
        System.out.println(totalbytes);