Question: How object automatically converted into JSON in RESTFull Webservice project?

Ans:

Spring’s HTTP message converter support, you don’t need to do this conversion manually. Because Jackson 2 is on the classpath, Spring’s MappingJackson2HttpMessageConverter is automatically chosen to convert the Class instance to JSON.

For this you have to import the below line

import org.codehaus.jackson.map.annotate.JsonSerialize;

For RESTFull Service you need to copy following jars and paste them inside WEB-INF -> lib folder in your project. Once you've done that, add those jars to your project build path as well. Into your  project build path as well.

asm-3.1.jar

jersey-client-1.17.1.jar

jersey-core-1.17.1.jar

jersey-server-1.17.1.jar

jersey-servlet-1.17.1.jar

jsr311-api-1.1.1.jar

Question : How to retrieving and Accessing Array Values in ResultSet

Answer:

As with the JDBC 4.0 large object interfaces (Blob, Clob, NClob), you can manipulate Array objects without having to bring all of their data from the database server to your client computer. An Array object materializes the SQL ARRAY it represents as either a result set or a Java array.

The following excerpt retrieves the SQL ARRAY value in the column ZIPS and assigns it to the java.sql.Array object z object. The excerpt retrieves the contents of z and stores it in zips, a Java array that contains objects of type String. The excerpt iterates through the zips array and checks that each postal (zip) code is valid. This code assumes that the class ZipCode has been defined previously with the method isValid returning true if the given zip code matches one of the zip codes in a master list of valid zip codes:

ResultSet rs = stmt.executeQuery("SELECT region_name, zips FROM REGIONS");

while (rs.next()) {

    Array z = rs.getArray("ZIPS");

    String[] zips = (String[])z.getArray();

    for (int i = 0; i < zips.length; i++) {

        if (!ZipCode.isValid(zips[i])) {

            // ...

            // Code to display warning

        }

    }

}

In the following statement, the ResultSet method getArray() returns the value stored in the column ZIPS of the current row as the java.sql.Array object z:

Array z = rs.getArray("ZIPS");

The variable z contains a locator, which is a logical pointer to the SQL ARRAY on the server; it does not contain the elements of the ARRAY itself. Being a logical pointer, z can be used to manipulate the array on the server.

In the following line, getArray is the Array.getArray method, not the ResultSet.getArray method used in the previous line. Because the Array.getArray method returns an Object in the Java programming language and because each zip code is a String object, the result is cast to an array of String objects before being assigned to the variable zips.

String[] zips = (String[])z.getArray();

The Array.getArray method materializes the SQL ARRAY elements on the client as an array of String objects. Because, in effect, the variable zips contains the elements of the array, it is possible to iterate through zips in a for loop, looking for zip codes that are not valid.