code example for Intelligent contract client and web-side invocation of event events for intelligent contracts __ Smart Contracts

code example for invoking event events for intelligent contracts on the client and web side Web Truffle

According to the official website example

Http://truffleframework.com/boxes/pet-shop

Truffle as a running test framework, it is also web3 to make calls to smart contracts.

The location where the file is located src/js/app.js

  Initweb3:function () {

      //Web3 entry
      if (typeof web3!== ' undefined ') {
          app.web3provider = Web3.currentprovider;
      else {
          //test network
          App.web3provider = new Web3.providers.HttpProvider (' http://localhost:8588 '); Here is the port I specified
      web3 = new Web3 (app.web3provider);

    return App.initcontract ();
  },

When the smart contract was initialized, it was invoked using the JSON file that truffle itself compiled

  Initcontract:function () {
      //load Adoption.json
      $.getjson (' Adoption.json ', function (data) {
          //Smart Contract instantiation
          var adoptionartifact = data;
          App.contracts.Adoption = Trufflecontract (adoptionartifact); Assign value to node data under App.contracts

          //Set contract provider
          App.contracts.Adoption.setProvider (app.web3provider);

          Retrieval Operation return
          app.markadopted ();
      });

    return app.bindevents ();//execute event binding
  },

This is how event bindings are implemented.

  Bindevents:function () {
    $ (document). On (' click ', '. btn-adopt ', app.handleadopt);
  },

Where btn-adopt corresponds to a button in the src/index.html

<button class= "btn btn-default btn-adopt" type= "button" data-id= "0" >Adopt</button>

After the environment is run, an element check is made and the button is found to bind the event

The bound method is defined below the JS file.

 Handleadopt:function () {event.preventdefault ();//This method notifies the Web browser not to perform the default action associated with the event (if there is such an action)

      var Petid = parseint ($ (event.target). Data (' ID '));

      var adoptioninstance;
          Web3.eth.getAccounts (function (error, accounts) {//essence or WEB3 call if (error) {Console.log (error);

          var account = Accounts[0];

              App.contracts.Adoption.deployed (). Then (function (instance) {adoptioninstance = instance;
          Execute adopt as a transaction by sending account return Adoptioninstance.adopt (Petid, {from:account}); }). Then (function (Result) {return app.markadopted ();////disable button disabled}
          {Console.log (err.message);
      });
  }); }

  Markadopted:function (adopters, account) {
      //instance
      var adoptioninstance;


      App.contracts.Adoption.deployed (). Then (function (instance) {
          adoptioninstance = instance;

          return AdoptionInstance.getAdopters.call ();
      }). Then (function (adopters) {for
          (i = 0; i < adopters.length; i++) {
              if (adopters[i)!== ' 0x0000000000000000000000 000000000000000000 ') {
                  $ ('. Panel-pet '). EQ (i). Find (' button '). Text (' Success '). attr (' disabled ', true);
              }
      }). catch (function (err) {
          console.log (err.message);
      });
  

Summary: The intelligent contract on the Web side uses the technology stack for Node + truffle + web3 to complete the writing, testing, and deployment. Client Java web3j

Project Open Source address is https://github.com/web3j/web3j

Because the role of WEB3J is the same as WEB3, it is a deployment call to a smart contract. Client Java qtum-android

The quantum chain official wallet client does not use WEB3J, but rather writes its own library.

Project Address is https://github.com/qtumproject/qtum-android

File as location App/src/main/java/org/qtum/wallet/utils/contractbuilder.java