远程从Mongodb 数据库中导出为CSV文件

Java 连接Mongodb 数据库并且从数据库导出数据为CSV文件。

需要导入三个包：

bson-3.4.3.jar
mongo-java-driver-3.4.3.jar

mongodb-driver-core-3.4.3.jar

当然版本可以改变。可以从http://mongodb.github.io/mongo-java-driver/ 这里下载

mongodb.properties：

url=localhost
port=27017
连接数据库的工具类：

package com.qitech.util;

import java.io.IOException;
import java.io.InputStream;
import java.net.UnknownHostException;
import java.util.Properties;

import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.Mongo;
import com.mongodb.MongoException;

public class MongoDbConn {
private static String url;
private static int port;

// 初始化加载
static{
//加载
Properties p = new Properties();
InputStream input = MongoDbConn.class.getClassLoader().getResourceAsStream("mongodb.properties");
try {
p.load(input);
url = p.getProperty("url");
port = Integer.valueOf(p.getProperty("port"));
} catch (IOException e) {
e.printStackTrace();
}finally{
if (input != null) {
try {
input.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
/**
* 获取连接mongodb
* @Description:
* @param @return
* @return DBCollection 返回类型
*/
public static DBCollection getConn(String db,String table) throws UnknownHostException{
DBCollection conn = null;
try {
@SuppressWarnings("deprecation")
Mongo m = new Mongo(url,port);
DB d = m.getDB(db);
conn = d.getCollection(table);
} catch (MongoException e) {
e.printStackTrace();
}
return conn;
}
/**
* 关闭连接
* @Description:
* @param @param m
* @return void 返回类型
*/
public static void getClose(Mongo m){
m.close();
}
}



导出CSV 文件的工具类：

package com.qitech.util;

import java.io.IOException;
import java.util.ArrayList;
import com.csvreader.CsvWriter;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;

public class WriteCsvUtil {
public static void Csv(DBCursor cursor,String fileName) throws IOException{
CsvWriter csvWriter = new CsvWriter(("F:/"+fileName));
//获取标题

DBObject ob = cursor.toArray().get(0);

ArrayList<String> title = new ArrayList<String>();
for(String key:ob.keySet()){
title.add(key);
}

String[] buffer = new String[100];
String[] buffer1 = new String[10000];

for(int i = 0;i< (cursor.count() + 1);i++){
int k=0;
//创建标题行
if(i == 0){
for(int j=0;j<title.size();j++){
buffer[k] = title.get(j);
k++;
}
continue;
}

if(i == 1){
csvWriter.writeRecord(buffer);
}

//写数据
DBObject obj = null;
for(int j = 0;j < title.size();j++){
int k1=0;
obj = cursor.toArray().get(i-1);
for(String key : obj.keySet()){
if (key.equals(title.get(j))) {
buffer1[k1] = obj.get(key).toString();
}
k1++;
}

}
csvWriter.writeRecord(buffer1);
}
try {

System.out.println("aaa");

} catch (RuntimeException r) {
// TODO Auto-generated catch block
new RuntimeException("导出CSV 文件出错");
}finally {
System.out.println("导出文件成功");
//csvWriter.flush();
csvWriter.close();
}
}
}



测试类：

public static void main(String[] args) throws IOException {
DBCollection conn = null;
try {
conn = MongoDbConn.getConn("local", "student");
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
DBCursor cursor = conn.find();

WriteCsvUtil.Csv(cursor, "1.csv");
}

导出截图：