Java 在多线程代码中访问数组列表的每个线程

我正在从事一个项目，在该项目中，我在不同的数据库中有两个具有不同模式的表。这意味着我有两个不同的连接参数用于使用JDBC连接这两个表-

假设下面是config.property文件

TABLES: table1 table2

#For Table1
table1.url: jdbc:mysql://localhost:3306/garden
table1.user: gardener
table1.password: shavel
table1.driver: jdbc-driver
table1.percentage: 80
table1.columns: COL1,COL2,COl3,Col4,COL5

#For Table2
table2.url: jdbc:mysql://otherhost:3306/forest
table2.user: forester
table2.password: axe
table2.driver: jdbc-driver
table2.percentage: 20
table1.columns: COL10,COL11,COl12,Col13,COL14

下面的方法将读取上面的

config.properties

文件，并为每个表创建一个

TableConnectionInfo

对象

private static void readPropertyFile() throws IOException {

    prop.load(LnPRead.class.getClassLoader().getResourceAsStream("config.properties"));

    tableNames = Arrays.asList(prop.getProperty("TABLES").trim().split(","));

    for (String arg : tableNames) {

        TableConnectionInfo ci = new TableConnectionInfo();
        ArrayList<String> columns = new ArrayList<String>();

        String table = prop.getProperty(arg + ".table").trim();
        columns = new ArrayList<String>(Arrays.asList(prop.getProperty(arg + ".columns").split(",")));

        ci.setTableName(table);
        ci.setColumns(columns);

        tableList.put(arg, ci);
    }
}   

现在，我正在为指定数量的线程创建

ExecutorService

，并将这个

tableList

对象（我通过读取

config.property文件创建的）传递给
任务类的构造函数
，然后这个
tableList
对象将不会被任何线程修改，只有每个线程将访问这些值-

// create thread pool with given size
ExecutorService service = Executors.newFixedThreadPool(10);

long startTime = System.currentTimeMillis();
long endTime = startTime + (durationOfRun * 60 * 1000);

for (int i = 0; i < threads; i++) {
    service.submit(new Task(endTime, tableList));
}

//创建具有给定大小的线程池
ExecutorService=Executors.newFixedThreadPool（10）；
long startTime=System.currentTimeMillis（）；
长结束时间=开始时间+（运行持续时间*60*1000）；
对于（int i=0；i

下面是我实现Runnable接口的任务类

class Task implements Runnable {

    private static Random random = new SecureRandom();
    private final long endTime;
    private final LinkedHashMap<String, TableConnectionInfo> tableLists;

    public Task(long endTime, LinkedHashMap<String, TableConnectionInfo> tableList) {
        this.endTime = endTime;
        this.tableLists = tableList;
    }

    @Override
    public void run() {

        while (System.currentTimeMillis() <= endTime) {

            .....

            double randomNumber = random.nextDouble() * 100.0;
            TableConnectionInfo table = selectRandomTable(randomNumber);

            /* Below line is Thread Safe right? 
             * And there won't be any issue with it? As I am doing
             * table.getColumns which will returns me an ArrayList of columns
             */
            final String columnsList = getTableColumns(table.getColumns());

            ....
        }
      }

     private String getTableColumns(final List<String> columns) {

      ...

     }
}

类任务实现可运行{
private static Random=new SecureRandom（）；
私人最终长时间；
私人最终LinkedHashMap表格列表；
公共任务（长结束时间，LinkedHashMap表列表）{
this.endTime=endTime；
this.tableList=tableList；
}
@凌驾
公开募捐{
while（System.currentTimeMillis（）这在技术上是线程安全的，只要基础ArrayList在初始构造后不发生更改。本例中的每个线程都将引用ArrayList的相同实例

如果将来有计划使这些表列可变，这将导致问题。如果此列表可变，我将构造一个新的列表和指针交换，或者使用java.util.concurrent.*类保存列列表

class Task implements Runnable {

    private static Random random = new SecureRandom();
    private final long endTime;
    private final LinkedHashMap<String, TableConnectionInfo> tableLists;

    public Task(long endTime, LinkedHashMap<String, TableConnectionInfo> tableList) {
        this.endTime = endTime;
        this.tableLists = tableList;
    }

    @Override
    public void run() {

        while (System.currentTimeMillis() <= endTime) {

            .....

            double randomNumber = random.nextDouble() * 100.0;
            TableConnectionInfo table = selectRandomTable(randomNumber);

            /* Below line is Thread Safe right? 
             * And there won't be any issue with it? As I am doing
             * table.getColumns which will returns me an ArrayList of columns
             */
            final String columnsList = getTableColumns(table.getColumns());

            ....
        }
      }

     private String getTableColumns(final List<String> columns) {

      ...

     }
}