mini-mongodb

模仿mongodb采用Xml+json實現小型數據庫;1.實現數據庫創建2.表的創建3.表數據的增、刪、改、查供大家參考學習使用，有助于更好的了解MongoDB的實現原理！ 代碼下載地址：?http://zhangdaiscott.github.io/mini-mogodb

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package org.jeecgframework;import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.UUID;import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; import org.jdom.output.XMLOutputter;import com.google.gson.Gson;public class MiniMogodb { private static final String _uuid = "_uuid"; /** * 獲取表的全部數據 *? * @param path * @param tablename * @return * @throws Exception */ public List<Map> loadTableDatas(String path, String tablename) throws Exception { Gson gson = new Gson(); FileInputStream file = new FileInputStream(path); SAXBuilder saxBuilder = new SAXBuilder(); Document document = saxBuilder.build(file); Element root = document.getRootElement(); List<Map> l = new ArrayList(); List<Element> list = root.getChildren(); for (Element x : list) { if (x.getAttributeValue("name").equals(tablename)) { List<Element> al = x.getChildren(); for (Element s : al) { String data = s.getText(); if (data == null) { break; } Map mp = gson.fromJson(data, Map.class); l.add(mp); } } } return l; } /** * 表插入數據 *? * @param path * @param tablename * @param po * @return * @throws JDOMException * @throws IOException */ public boolean addData(String path, String tablename, Object po) throws JDOMException, IOException { Gson gson = new Gson(); boolean flag = false; FileInputStream file = new FileInputStream(path); SAXBuilder saxBuilder = new SAXBuilder(); Document document = saxBuilder.build(file); Element root = document.getRootElement(); List<Element> list = root.getChildren(); for (Element x : list) { if (x.getAttributeValue("name").equals(tablename)) { Map base = new HashMap(); base.put(_uuid, UUID.randomUUID().toString()); Element data = new Element("data"); String json = gson.toJson(po); Map mp = gson.fromJson(json, Map.class); base.putAll(mp); data.addContent(gson.toJson(base)); x.addContent(data); } } XMLOutputter out = new XMLOutputter(); out.output(document, new FileOutputStream(path)); flag = true; System.out .println("----------insert --- data --- success----------------------"); return flag; } /** * 表修改數據 *? * @param path * @param tablename * @param po * @throws JDOMException * @throws IOException */ public void updateData(String path, String tablename, Object po) throws JDOMException, IOException { FileInputStream file = new FileInputStream(path); SAXBuilder saxBuilder = new SAXBuilder(); Document document = saxBuilder.build(file); Element root = document.getRootElement(); Gson gson = new Gson(); List<Element> list = root.getChildren(); for (Element x : list) { if (x.getAttributeValue("name").equals(tablename)) { List<Element> al = x.getChildren(); for (Element s : al) { // 如果定位Data[通過UUID唯一標示] Map mp = gson.fromJson(s.getText(), Map.class); Map newmp = gson.fromJson(gson.toJson(po), Map.class); if (mp.get(_uuid).equals(newmp.get(_uuid))) { mp.putAll(newmp); Element data = new Element("data"); data.setText(gson.toJson(mp)); x.removeContent(s); x.addContent(data); break; } } } } XMLOutputter out = new XMLOutputter(); out.output(document, new FileOutputStream(path)); System.out .println("----------update --- data --- success----------------------"); } /** * 表刪除數據 *? * @param path * @param tablename * @param po * @throws JDOMException * @throws IOException */ public void deleteData(String path, String tablename, Object po) throws JDOMException, IOException { FileInputStream file = new FileInputStream(path); Gson gson = new Gson(); SAXBuilder saxBuilder = new SAXBuilder(); Document document = saxBuilder.build(file); Element root = document.getRootElement(); List<Element> list = root.getChildren(); for (Element x : list) { List<Element> al = x.getChildren(); if (x.getAttributeValue("name").equals(tablename)) { for (Element s : al) { // 如果定位Data[通過UUID唯一標示] Map mp = gson.fromJson(s.getText(), Map.class); Map newmp = gson.fromJson(gson.toJson(po), Map.class); if (mp.get(_uuid).equals(newmp.get(_uuid))) { x.removeContent(s); break; } } } } XMLOutputter out = new XMLOutputter(); out.output(document, new FileOutputStream(path)); System.out .println("----------delete --- data --- success----------------------"); } /** * 創建數據庫 *? * @param path * @throws Exception */ public void createDataBase(String path) throws Exception { FileOutputStream file1 = new FileOutputStream(path); Document document = new Document(); Element root = new Element("database"); Element sort1 = new Element("table"); sort1.setAttribute("name", "test"); Element sort2 = new Element("table"); sort2.setAttribute("name", "system.indexs"); Element sort3 = new Element("table"); sort3.setAttribute("name", "system.users"); root.addContent(sort1); root.addContent(sort2); root.addContent(sort3); document.setRootElement(root); XMLOutputter out = new XMLOutputter(); out.output(document, file1); System.out .println("----------create---database---success-------------------"); } } <?xml version="1.0" encoding="UTF-8"?> <database> <table name="test"> <data>{"sex":"男","age":20.0,"name":"lisan","money":2000.98,"_uuid":"a2b64d1a-63ea-4a1b-b1e3-67adcc687c0a"} </data> </table> <table name="system.indexs" /> <table name="system.users" /> </database>

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