Java防止SQL注入的幾個途徑

Java防SQL注入，最簡單的辦法是杜絕SQL拼接，SQL注入攻擊能得逞是因為在原有SQL語句中加入了新的邏輯，如果使用PreparedStatement來代替Statement來執行SQL語句，其後只是輸入參數，SQL注入攻擊手段將無效，這是因為PreparedStatement不允許在不同的插入時間改變查詢的邏輯結構，大部分的SQL注入已經擋住了，在WEB層我們可以過濾用戶的輸入來防止SQL注入比如用Filter來過濾全局的表單參數。

import Java.io.IOException;  
import Java.util.Iterator;  
import Javax.servlet.Filter;  
import Javax.servlet.FilterChain;  
import Javax.servlet.FilterConfig;  
import Javax.servlet.ServletException;  
import Javax.servlet.ServletRequest;  
import Javax.servlet.ServletResponse;  
import Javax.servlet.http.HttpServletRequest;  
import Javax.servlet.http.HttpServletResponse;  
/**  
* 通過Filter過濾器來防SQL注入攻擊  
*  
*/ 
public class SQLFilter implements Filter {  
private String inj_str = "'|and|exec|insert|select|delete|update|count|*|%|chr|mid|master|truncate|char|declare|; |or|-|+|,";  
protected FilterConfig filterConfig = null;  
/**  
* Should a character encoding specified by the clIEnt be ignored?  
*/ 
protected boolean ignore = true;  
public void init(FilterConfig config) throws ServletException {  
this.filterConfig = config;  
this.inj_str = filterConfig.getInitParameter("keyWords");  
}  
public void doFilter(ServletRequest request, ServletResponse response,  
FilterChain chain) throws IOException, ServletException {  
HttpServletRequest req = (HttpServletRequest)request;  
HttpServletResponse res = (HttpServletResponse)response;  
Iterator values = req.getParameterMap().values().iterator();//獲取所有的表單參數  
while(values.hasNext()){  
String[] value = (String[])values.next();  
for(int i = 0;i < value.length;i++){  
if(sql_inj(value[i])){  
//TODO這裡發現sql注入代碼的業務邏輯代碼  
return;  
}  
}  
}  
chain.doFilter(request, response);  
}  
public boolean sql_inj(String str)  
{  
String[] inj_stra=inj_str.split("\\|");  
for (int i=0 ; i < inj_stra.length ; i++ )  
{  
if (str.indexOf(" "+inj_stra[i]+" ")>=0)  
{  
return true;  
}  
}  
return false;  
}  
} 

也可以單獨在需要防范SQL注入的JavaBean的字段上過濾：

/**  
* 防止sql注入  
*  
* @param sql  
* @return  
*/ 
public static String TransactSQLInjection(String sql) {  
return sql.replaceAll(".*([';]+|(--)+).*", " ");