最近用BDB写点东西，写了挺多个测试工程。列下表，也理清楚最近的思路
1.测试BDB程序，包括打开增加记录，查询记录，获取所有记录。将数据转存mysql
程序的不足，增加记录仅仅只有key和value，查询记录仅仅是简单的根据key或者同时制定key和value来查，只获取所有记录，没有获取部分记录，转存mysql消耗比较大
2.mysql和BDB插入和选择数据比较。
在java虚拟机内存相同的条件下，mysql插入数据量比较大时会报内存溢出，BDB 插入数据的量可以比mysql大。而且速度也快。查询所有记录mysql非常快，BDB相对来说比较慢，hbase只测试了下插入记录，插入一千条记录都慢得要死。单个数据选择BDB相对于mysql来说有绝对的优势。
3.修改1中的数据转存mysql。通过两台电脑，两个BDB+mysql进行。
大致流程是一个一台电脑A上有BDB，另外一台电脑B上有BDB和mysql。A上采集数据存储在BDB中。然后自己写一个文件发送的程序把BDB在硬盘上的.jdb文件发送到另外一台电脑。另外一台电脑通过BDB读取.jdb文件写进mysql里面。运行效果比较好，但是时间比直接插入一千万条记录进BDB要长。现在没看到应用领域。
4.序列化存储。实现用BDB存储学生信息
5.BDB游标的使用。对比getSearchKey,getSearchBoth,getSearchKeyRange,getSearchBothRange函数。最后写了个key的模糊查询。
以上基本上是一个星期学到的有关Berkeley DB的知识。
getSearchKey,getSearchBoth,getSearchKeyRange,getSearchBothRange对比程序
import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList; import com.sleepycat.je.Cursor;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseConfig;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentConfig;
import com.sleepycat.je.LockMode;
import com.sleepycat.je.OperationStatus; public class Query {
private Environment dbEnvironment = null;
private Database db = null; private void DataConstruct(int t) throws UnsupportedEncodingException {
int Total = t;
long BDBTime = 0;
long start = System.currentTimeMillis();
/*
*
*/
OpenBDB();
while(Total!=0)
{ int k = Total;
int v = Total+1;
DatabaseEntry iKey = new DatabaseEntry(Integer.valueOf(k).toString().getBytes("UTF-8"));
DatabaseEntry iValue = new DatabaseEntry(Integer.valueOf(v).toString().getBytes("UTF-8")); //System.out.println("Writing : Key= " + k + " Value = " + v + " count: " + Total); db.put(null, iKey, iValue);
Total--;
}
long end = System.currentTimeMillis();
BDBTime = end - start;
System.out.println(BDBTime); } //各种查询比较 public void QueryCompare(int t) throws UnsupportedEncodingException{ DataConstruct(t);
//OpenBDB(); Cursor cursor = null;
cursor = db.openCursor(null, null); DatabaseEntry thekey = new DatabaseEntry();
String key = "12345";
thekey.setData(key.getBytes("utf-8")); DatabaseEntry thedata = new DatabaseEntry(); System.out.println(" >======== getSearchKey Start ========<");
cursor.getSearchKey(thekey, thedata, LockMode.DEFAULT);
byte[] temp = thedata.getData();
String res = new String(temp,"utf-8");
System.out.println(" Key " + key + " Value " + res);
System.out.println(" >======== getSearchKey End ========<");
System.out.println(); System.out.println(" >======== getSearchKeyRange Start ========<");
cursor.getSearchKeyRange(thekey, thedata, LockMode.DEFAULT);
temp = thedata.getData();
res = new String(temp,"utf-8");
System.out.println(" Key " + key + " Value " + res);
System.out.println(" >======== getSearchKeyRange End ========<");
System.out.println(); //如果要执行这个查询最后不用随机数，用随机数相查到结果不易
System.out.println(" >======== getSearchBoth Start ========<");
thedata.setData("12346".getBytes("utf-8"));
OperationStatus status = cursor.getSearchBoth(thekey, thedata, LockMode.DEFAULT);
if(status == OperationStatus.SUCCESS){
temp = thedata.getData();
res = new String(temp,"utf-8");
System.out.println(" Key " + key + " Value " + res);
}
else
System.out.println(" Not Such Record"); System.out.println(" >======== getSearchKeyBoth End ========<");
System.out.println(); System.out.println(" >======== getSearchBothRange Start ========<");
thedata.setData("123451".getBytes("utf-8"));
status = cursor.getSearchBoth(thekey, thedata, LockMode.DEFAULT);
if(status == OperationStatus.SUCCESS){
temp = thedata.getData();
res = new String(temp,"utf-8");
System.out.println(" Key " + key + " Value " + res);
}
else
System.out.println(" Not Such Record");
System.out.println(" RecordCount: " + cursor.count()); System.out.println(" >======== getSearchKeyBothRange End ========<");
System.out.println(); /*
* getSearchKeyRange和getSearchKey都是将游标定位到匹配key值相同的地方，如果再用Cursor.getNext无论如何都是能得到游标下一个。区别是当用到B树的时候
* 根据getSearchKeyRange和getSearchKey和Cursor.getNext的输出结果的规律可以看出，BDB内部存储采用树形结构，类似字符数
* getSearchBoth同时匹配Key和Value才有结果，才能返回OperationStatus.SUCCESS才算操作成功
*
*/
/*
* 实现模糊查询，用getSearchKey配合getNext即可
*
*/
//单条件模糊查询测试代码,匹配12345,结束应该是12346 System.out.println(" >======== Simple Pattern key = 12345 getSearchKey Start ========<");
thedata = new DatabaseEntry();//单条件查询，把之前的thedata设置为空
cursor.getSearchKeyRange(thekey, thedata, LockMode.DEFAULT);
temp = thedata.getData(); //
res = new String(temp,"utf-8");
System.out.println(" Key " + key + " Value " + res);
thekey = new DatabaseEntry();
while(cursor.getNext(thekey, thedata, LockMode.DEFAULT) != OperationStatus.NOTFOUND){ //结束条件是OperationStatus.NOTFOUND
temp = thedata.getData();
byte[] tempkey = thekey.getData();
res = new String(temp,"utf-8");
String res1 = new String(tempkey,"utf-8");
if(res1.equals("12346"))
break;
System.out.println(" Key " + res1 + " Value " + res);
}
System.out.println(" >======== Simple getSearchKey End ========<");
System.out.println(); //多条件模糊查询，如果没有相应的机制只能自己编写来查了,
//失败 System.out.println(" >======== multiplication Pattern Key=12345 Value = 123451 getSearchBothRange Start ========<");
thedata.setData("123451".getBytes("utf-8"));
thekey.setData(key.getBytes("utf-8"));
status = cursor.getSearchBothRange(thekey, thedata, LockMode.DEFAULT);
//首先会去匹配12345 123456
if(status==OperationStatus.SUCCESS){
temp = thedata.getData(); //
res = new String(temp,"utf-8");
System.out.println(" Key " + key + " Value " + res);
while(cursor.getNext(thekey, thedata, LockMode.DEFAULT) != OperationStatus.NOTFOUND){ //结束条件是OperationStatus.NOTFOUND
temp = thedata.getData();
byte[] tempkey = thekey.getData();
res = new String(temp,"utf-8");
String res1 = new String(tempkey,"utf-8");
if(res1.equals("12346"))
break;
System.out.println(" Key " + res1 + " Value " + res);
}
}
else
System.out.println(" Not Such Record"); System.out.println(" >======== multiplication getSearchBothRange End ========<");
System.out.println();
cursor.close();
CloseBDB(); } //创建数据库
public void OpenBDB(){
EnvironmentConfig envConfig = new EnvironmentConfig();
envConfig.setAllowCreate(true);
dbEnvironment = new Environment( new File("D:/dbEnv"), envConfig );
DatabaseConfig dbConfig = new DatabaseConfig(); dbConfig.setAllowCreate(true);
dbConfig.setSortedDuplicates(true);
db = dbEnvironment.openDatabase(null,"BDB", dbConfig);
System.out.println("打开数据库成功");
}
//关闭数据库
public void CloseBDB(){
if(db != null){
db.close();
}
if(dbEnvironment != null){
dbEnvironment.close();
}
} //获取数据库中所有记录，
public ArrayList<String> getEveryItem() throws UnsupportedEncodingException {
Cursor cursor = null;
OpenBDB();
cursor= db.openCursor(null,null);
DatabaseEntry theKey=null;
DatabaseEntry theData=null;
theKey = new DatabaseEntry();
theData = new DatabaseEntry();
long total = 0;
ArrayList<String> list = new ArrayList<String>(); while (cursor.getNext(theKey, theData, LockMode.DEFAULT) == OperationStatus.SUCCESS) {
//System.out.println("Reading: Key: " + new String( theKey.getData()) + "Value: " + new String(theData.getData()));
list.add(new String( theKey.getData()) );
list.add(new String( theData.getData()) );
total++;
}
cursor.close();
System.out.println("total:" + total);
return list; } //getSearchKey }
序列化创建学生信息
import java.io.File; import com.sleepycat.bind.EntryBinding;
import com.sleepycat.bind.serial.SerialBinding;
import com.sleepycat.bind.serial.StoredClassCatalog;
import com.sleepycat.je.Cursor;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseConfig;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentConfig;
import com.sleepycat.je.LockMode;
import com.sleepycat.je.OperationStatus; public class SeriableDemo { public static void main(String args[]){
Environment dbEnv = null;
Database db = null;
Cursor cursor=null;
try { EnvironmentConfig envconfig = new EnvironmentConfig();
envconfig.setAllowCreate(true);
dbEnv = new Environment(new File("D:/dbEnv/"),envconfig); DatabaseConfig dbconfig = new DatabaseConfig();
dbconfig.setAllowCreate(true);
dbconfig.setReadOnly(false);
dbconfig.setSortedDuplicates(false);
//data
db = dbEnv.openDatabase(null, "Student_Data", dbconfig);
//class
Database myclassdb=dbEnv.openDatabase(null, "Student_class", dbconfig);
//cataglog存储类信息
StoredClassCatalog classCatalog =new StoredClassCatalog(myclassdb); //创建绑定对象
EntryBinding dataBinging=new SerialBinding(classCatalog,Student.class); DatabaseEntry thekey=new DatabaseEntry("".getBytes("utf-8"));
DatabaseEntry thedata=new DatabaseEntry();
Student st=new Student(); st.setStudentId();
st.setStudentName("邹颖玖");
st.setStudentAge();
st.setStudentDept("计算机科学与工程"); //绑定数据
dataBinging.objectToEntry(st, thedata);
//插入
db.put(null, thekey, thedata); DatabaseEntry data = new DatabaseEntry();
//DatabaseEntry key = new DatabaseEntry();
DatabaseEntry key = new DatabaseEntry("".getBytes("utf-8"));
Student st1 = new Student();
st1.setStudentId();
dataBinging.objectToEntry(st1, data);
//获取
OperationStatus status=db.get(null, key, data, LockMode.DEFAULT);
if(status==OperationStatus.SUCCESS){
Student s=(Student) dataBinging.entryToObject(thedata);
System.out.println(s.getStudentId()+" "+s.getStudentName()+" "+
s.getStudentAge() + " " + s.getStudentDept());
} }catch(Exception e){
e.printStackTrace();
}
}
}
上面代码用到学生类。
import java.io.Serializable;
public class Student implements Serializable {
private long StudentId;
private String StudentName;
private int StudentAge;
private String StudentDept;
public long getStudentId() {
return StudentId;
}
public void setStudentId(long studentId) {
StudentId = studentId;
}
public String getStudentName() {
return StudentName;
}
public void setStudentName(String studentName) {
StudentName = studentName;
}
public int getStudentAge() {
return StudentAge;
}
public void setStudentAge(int studentAge) {
StudentAge = studentAge;
}
public String getStudentDept() {
return StudentDept;
}
public void setStudentDept(String studentDept) {
StudentDept = studentDept;
}
}
以上是老师将来项目需要，估计以后我也有这种需要。没有时间，还是想自己实践弄一套音乐推荐系统出来。