http断点续传简单实现（java)

/* z*~PYAt  
**SiteFileFetch.java YB1DL^:  
*/ H_=[~mJ  
package NetFox; jMWwu+w  
import java.io.*; z==}~|5  
import java.net.*; 8lGgp&ey  
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public class SiteFileFetch extends Thread { V;]VwsZ
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SiteInfoBean siteInfoBean = null; //文件信息Bean & O\!!1%  
long[] nStartPos; //开始位置 -XIvj'u  
long[] nEndPos; //结束位置 :O+b
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 "v(]"L  
long nFileLength; //文件长度 rZQHB[^3  
boolean bFirst = true; //是否第一次取文件 'yRv~BA  
boolean bStop = false; //停止标志 )0d".Q|v4  
File tmpFile; //文件下载的临时信息 2OlC7X{  
DataOutputStream output; //输出到文件的输出流 :9q^  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） s^R2jueR  
public SiteFileFetch(SiteInfoBean bean) throws IOException HtYR 0J  
{ 78~V/L;@S2  
siteInfoBean = bean; iSLf:  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 2co{9LM  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ayz1i:Q|  
if(tmpFile.exists ())  /r@  
{ /_\W*@ E  
bFirst = false; D c.WvU
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read_nPos(); |F{E4mg(o  
} sZBO_](S  
else aMg f6veM  
{ 6Q.whV%y  
nStartPos = new long[bean.getNSplitter()]; G*p.JsZP  
nEndPos = new long[bean.getNSplitter()]; \#7%%>p=O'  
} jV&W[xKa  
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} \J&#C(pn  
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public void run() l<_mag/j9o  
{ sc>)X{eb  
//获得文件长度 0%j;yzQ<  
//分割文件 S9+gVR8]C  
//实例FileSplitterFetch !O_^Rn+<2  
//启动FileSplitterFetch线程 8>;o MM  
//等待子线程返回 t1g%o5?;  
try{ D ,^ U%<`  
if(bFirst) BTtYlpN6  
{ ?+o7Y1 k,  
nFileLength = getFileSize(); 4<Y[L'UaA@  
if(nFileLength == -1) R!xc$`N  
{ lfd{O7L0b  
System.err.println("File Length is not known!"); 1K',Vw_  
} 4zbV' ]  
else if(nFileLength == -2) q`zR6  
{ F$p,xFH#  
System.err.println("File is not access!"); SYLkC [0k  
} uoc-qmm  
else |.nWy"L  
{ <)rH8]V  
for(int i=0;i<nStartPos.length;i++) ')~HOCBSE  
{ WTN!2b  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 74wa  
} rVmO/Y#Hx$  
for(int i=0;i<nEndPos.length-1;i++) vbJMgdHFR  
{ * OFT)S  
nEndPos = nStartPos[i+1]; 2mG?ve%m)  
} x9s`H)  
nEndPos[nEndPos.length-1] = nFileLength; )A;<'{t #L  
} X~!?t}  
} ]x
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//启动子线程 Q&{5.}L  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; "<b84?V5  
for(int i=0;i<nStartPos.length;i++) Q"uu&JC  
{ e#{L
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), NYRNop( N#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), =2'^:4Z  
nStartPos,nEndPos,i); Rvo<ISp  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); F@3,>~[%I  
fileSplitterFetch.start(); qpCi61lTDJ  
} [r'M_foga*  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), (>23[;.0  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); S_=uv)%a  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", #{sb>^BF  
nEndPos = " + nFileLength); ~coG8r"o  
// fileSplitterFetch[nPos.length-1].start(); -n-X/M  
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//等待子线程结束 Atw^C+"vW&  
//int count = 0; uqH;1T;s  
//是否结束while循环 ]T`qPIf;yJ  
boolean breakWhile = false; yKJp37R  
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while(!bStop) !h\3cs`QU  
{ 7)#/I  
write_nPos(); c$;enAf@  
Utility.sleep(500); !j@ 8:j0WY  
breakWhile = true; *']RYu?X  

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for(int i=0;i<nStartPos.length;i++) dewu@  
{
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if(!fileSplitterFetch.bDownOver) &ReIe>L  
{ M?o`tWLhF  
breakWhile = false; s zg1.&  
break; MDpXth7  
} ) AIZE?oX  
} F=H=[pSe  
if(breakWhile) U?>cm`DBP  
break; _ U\vHa$#  
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//count++; y[vjqfdmU  
//if(count>4) +}n]A^&I\E  
// siteStop(); Z3d&I]Tf  
} ]_h"2|  
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System.err.println("文件下载结束！"); j:
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} dxA=gL2  
catch(Exception e){e.printStackTrace ();} LYKepk  
} @S}'_g   
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//获得文件长度 7@`(DU`z  
public long getFileSize() VybiuP  
{ 1/z1~:Il  
int nFileLength = -1; D
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try{ E5rNC/Ul$$  
URL url = new URL(siteInfoBean.getSSiteURL()); '=r.rW5  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); SWu=n1J.?H  
httpConnection.setRequestProperty("User-Agent","NetFox"); #Jn_"cCRLx  
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int responseCode=httpConnection.getResponseCode(); =3@^TW(j  
if(responseCode>=400) y ^YrGz.  
{ R_lNC]b0  
processErrorCode(responseCode); #M
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return -2; //-2 represent access is error ]
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} mU*GcWbc+  
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String sHeader; `VHm,g2  
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#xO`k1W.  
for(int i=1;;i++) >IRo
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{ k&Sg`'LG8  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 6A%Y/o
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//Utility.log(in.readLine()); `/"z.~8  
sHeader=httpConnection.getHeaderFieldKey(i); {#7t(:x  
if(sHeader!=null) v^e[`]u(  
{ k07O.9>  
if(sHeader.equals("Content-Length")) o;"!#Z 1SJ  
{ :`_wy-}V  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 4kx#=MLt
 
break; /GEqU^ B  
} 7UMsKE-  
} p{.EFa>H  
else pPh$Jvo]  
break; BV<LIrAS  
} B-o"Y'iXs  
} ;R/=9l  
catch(IOException e){e.printStackTrace ();} ^E5Xpza  
catch(Exception e){e.printStackTrace ();} 0O[q6!&]  
pxP7yJL`  
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Utility.log(nFileLength); 8R)*8bb  
7^S&g.A  
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return nFileLength; $)kIYM&  
} ]Dx5t&  
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+W-sb5)  
//保存下载信息（文件指针位置） zVp|%&  
private void write_nPos() rGx1>xd(k  
{ <>p\9rVp*^  
try{ lQoa[#q  
output = new DataOutputStream(new FileOutputStream(tmpFile)); P[^!Uq[0n7  
output.writeInt(nStartPos.length); R9{6$djq\:  
for(int i=0;i<nStartPos.length;i++) jo+T!CUM'  
{ ^M8\ 3G  
// output.writeLong(nPos); ,)%nLc  
output.writeLong(fileSplitterFetch.nStartPos); w!%Bc]  
output.writeLong(fileSplitterFetch.nEndPos); oU67<jq  
} 24]O0K  
output.close(); }&ZO q'B  
} OfIml.  
catch(IOException e){e.printStackTrace ();} CI ~+(+q  
catch(Exception e){e.printStackTrace ();} UtY<R  
} I8e{%PK  
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5
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//读取保存的下载信息（文件指针位置） R$wo{{KX  
private void read_nPos() g5_]^[upw  
{ v"\Q/5p  
try{ =f?|f  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 0lY.z$V  
int nCount = input.readInt(); .z)&#2E  
nStartPos = new long[nCount]; -k")#1  
nEndPos = new long[nCount]; a'W-&j  
for(int i=0;i<nStartPos.length;i++) Y[@$1{YS  
{ 6imDA]5N&
 
nStartPos = input.readLong(); r>A,7{  
nEndPos = input.readLong();  pb6z)8  
} PudwcP{  
input.close(); 7l%O:M(\  
} E*i <P  
catch(IOException e){e.printStackTrace ();} 02SFFqm  
catch(Exception e){e.printStackTrace ();} n:x6bPal]  
} !Zlvz%X  
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private void processErrorCode(int nErrorCode)  UcKpid  
{ 9g|o17  
System.err.println("Error Code : " + nErrorCode); ldO6W7G|h  
} Si.3Je[q  
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//停止文件下载 mtvfG  
public void siteStop() t,)`Zu$  
{ w
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bStop = true; ;n?H/(6X8>  
for(int i=0;i<nStartPos.length;i++) 9Qst5n\Z  
fileSplitterFetch.splitterStop(); 8%@7G*  
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} ]SA]{id+  
} C{H:-"\J9  
//负责部分文件的抓取 >T'^&l(:  
**FileSplitterFetch.java PVC\&YF  
*/ I&,gCZ#  
package NetFox; hB]4Tn5H  
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import java.io.*; \=P+]9  
import java.net.*; A(S=  
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public class FileSplitterFetch extends Thread { KP(RK4F  
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String sURL; //File URL ~G+o;N,V  
long nStartPos; //File Snippet Start Position zUF%`CR  
long nEndPos; //File Snippet End Position y
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int nThreadID; //Thread's ID :FcYjw  
boolean bDownOver = false; //Downing is over Dl_y[9  
boolean bStop = false; //Stop identical I<PKwT/?  
FileAccessI fileAccessI = null; //File Access interface $iu{u|VSu  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 'mx_]b^O  
{ Y??
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this.sURL = sURL; _1TSt%L  
this.nStartPos = nStart; 4
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this.nEndPos = nEnd; NZ`Mq  
nThreadID = id; mMo<C_~w&  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 &.~Xl:lq  
} s wgn( -  
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t F^|,9_<  
public void run() =23JE'^=  
{ 46^LPC"x  
while(nStartPos < nEndPos && !bStop) I`"B<=zi  
{ WPLM*]6  
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try{ q):Ph&'r  
URL url = new URL(sURL); N]qX^RSb  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); iX ;E"ov]  
httpConnection.setRequestProperty("User-Agent","NetFox"); u7R:7$H  
String sProperty = "bytes="+nStartPos+"-"; Q(Uj5aX  
httpConnection.setRequestProperty("RANGE",sProperty); DY]\@<ez  
Utility.log(sProperty); V-rzn171Q)  
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InputStream input = httpConnection.getInputStream(); 1QkAFSl3  
//logResponseHead(httpConnection); e]N?{s   
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byte[] b = new byte[1024]; p%Zx<=f-_  
int nRead; ODE9@]a
  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) PP{2{  
{ Sg$14B  
nStartPos += fileAccessI.write(b,0,nRead); |/LCwq%  
//if(nThreadID == 1) @H'pvFLK?  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Ga o(3Y  
} L\p@1N?K  
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Utility.log("Thread " + nThreadID + " is over!"); b.Wf*I?  
bDownOver = true; ("HT0&#a  
//nPos = fileAccessI.write (b,0,nRead); OW$? 6  
} %DJxUuh  
catch(Exception e){e.printStackTrace ();} 8!e1T,:b  
} RJMrSz$  
} :

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)2c[]d/a4  
//打印回应的头信息 S].=gR0:  
public void logResponseHead(HttpURLConnection con) U?dd+2^};t  
{ y~jKytq^@  
for(int i=1;;i++) Q<]~>cd^  
{ T?=[6  
String header=con.getHeaderFieldKey(i); vF45tw  
if(header!=null) \qPgQsy4  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); -#XNZy!//  
Utility.log(header+" : "+con.getHeaderField(header)); 4qw&G  
else I<Vh Eo,  
break; UYu 54`'kg  
} XWo=?(iA  
} r{m"E^K,  
*.ffyBI*~  
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public void splitterStop() Q7PqN1jTE  
{ m .2)P~a  
bStop = true; m4:b?[  
} F*WWv&\X  
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} HaeF`gI^Ee  
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/* eW*nRha  
**FileAccess.java &Vi"m!Bf  
*//文件访问(定位，写) rnxO2   
package NetFox; *(&,&$1K  
import java.io.*; 7M:0%n$
 
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public class FileAccessI implements Serializable{ DvnK_Q!  
8<u_ wt@  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 5v8&C2Jy@  
RandomAccessFile oSavedFile; ]4@z.1Mr  
long nPos; <wTkPErUG  
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public FileAccessI() throws IOException zx{\SU  
{ NW
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this("",0); $Vp&Vc8  
} \@4QG.3&  
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public FileAccessI(String sName,long nPos) throws IOException kYs2AzS{d  
{ T$%u=$E%F  
oSavedFile = new RandomAccessFile(sName,"rw"); t]FFGnBZ  
this.nPos = nPos; V&KH{j/P  
oSavedFile.seek(nPos); -GP+e`d  
} qd3B>f  
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public synchronized int write(byte[] b,int nStart,int nLen) I}
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{ )+w0NhJw  
int n = -1; &nPv%P,e  
try{ [sz#*IJ  
oSavedFile.write(b,nStart,nLen); 2ok>z$Y  
n = nLen; k` (_~/#  
} )
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catch(IOException e) Tjure]wQz  
{ $K<jmEC@<  
e.printStackTrace (); OAw/  
} h.'h L  
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return n; 3{CGYd]_u  
} */\dH<  
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c  
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} Mw'd<{  
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!;CY @=  
/* 3CQpe  
**SiteInfoBean.java L/nz95  
*/ P'ZWAxd  
package NetFox; ~,':PUkiV  
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public class SiteInfoBean { l`$f@'k  
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private String sSiteURL; //Site's URL {AIZ,  
private String sFilePath; //Saved File's Path MiOSSl};  
private String sFileName; //Saved File's Name zKV{JUpG  
private int nSplitter; //Count of Splited Downloading File UQW;!8J#R(  
5-u=ZB%p  
s?%1/&.~  
public SiteInfoBean() bk4%lYJ"  
{//nSplitter的缺省值为5 :^iR&`2~  
//default value of nSplitter is 5 m@HU;J\I  
this("","","",5); 6oUT+^z#  
} v/yk T9@;  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) NmtBn^t  
{ Pi*,&D>{7  
sSiteURL= sURL; 1YnDho;~  
sFilePath = sPath;  pd X9G  
sFileName = sName; t]vX9vv+D  
this.nSplitter = nSpiltter; 9pjk3a  
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} c yN_Sg  
,hOJe=u46  
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public String getSSiteURL() Y}f%/vus  
{ Lwv9oa|  
return sSiteURL; >Xb]n_`  
} J::SFu=  
NWNgh/9?  
3rR(>}:[V  
public void setSSiteURL(String value) vB.LbYyF  
{ H9jj**W ;$  
sSiteURL = value; ruE.0VI@  
} !EKF^n6  
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((?^B  
public String getSFilePath() 1y?TyUP  
{ 9CL&tpqv f  
return sFilePath; (iS9
4}-)  
} ZGp8$Y>r  
`,7BU??+u  
t~bjDV^`  
public void setSFilePath(String value) .eeM&n;c  
{ u(REEc~nj  
sFilePath = value; &_-~kU1K^  
} p$"*U[%l  
a!>AhOk.  
+"d{P,[3J  
public String getSFileName() ("9)=x*5  
{
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return sFileName; ZsV'-gu  
} ]AfeaU'>  
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i
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public void setSFileName(String value) &i!.6M2  
{ q&P"  
sFileName = value; WS,p}:yPZG  
} \GPWC}V\s  
,Ma$:6`f  
&Wn!W  
public int getNSplitter() 7qnw.7p  
{ < Gu s9^_  
return nSplitter; b2:CFtH5  
} 1g|H8CA  
0gnr@9,X  
E7 7Au;TL  
public void setNSplitter(int nCount) #&$4tTl  
{ 58=fT1 B  
nSplitter = nCount; %3~jg  
} 1o.]"~0:  
} T@f$w/15  
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/* `@eQL[Z9x  
**Utility.java 'S&5zwrH  
*/ 6R"& !.ZF  
package NetFox; EXo"F*gW  
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public class Utility { ;B!&( 50e  
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public Utility() d+z8^$z"  
{ OCF=)#}qd  
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} O-
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i]YH"t8GY  
//线程睡眠 ^|OxlfS  
public static void sleep(int nSecond) !.kj-==s{7  
{ Lw2EA 5  
try{ 7)<&,BWc  
Thread.sleep(nSecond); 02?y%  
} &@nI(PXv  
catch(Exception e) j#.Aiy:,  
{ *<]ulR2  
e.printStackTrace (); bm`x  
} }zj_Pp  
} Qp]V~s(  
$,F1E VJ  
//日志 THkg,*;:  
public static void log(String sMsg) r ",..{  
{ PkMN@JS  
System.err.println(sMsg); MBp%TX!  
} M;-PrJdyt  
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public static void log(int sMsg) ?s6v>#H%  
{ &M&*3  
System.err.println(sMsg); J>TNyVaoQ  
} fl9`Mgu  
} fX2sjfk  
*%E4,(T  
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/* whxTCI
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**TestMethod.java C6Lc  
*/ F2QFQX(j  
package NetFox; Y 3h`uLQ  
kUGOkSP8[  
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public class TestMethod { [;t-XC?[nk  
-n FKP&P  
xy))}c%  
public TestMethod() "ngULpb{R  
{ ///xx/weblogic60b2_win.exe ' Dcj\=8
 
try{ xsu9DzPf&{  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 0Un?[O  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 0Q?)?8_  
SiteFileFetch fileFetch = new SiteFileFetch(bean); VK286[[fv  
fileFetch.start(); :e1kpQ  
} 2[j(C  
catch(Exception e){e.printStackTrace ();} u}3D'h  
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} ~jC+6v  
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public static void main(String[] args) B6=
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{ V6Mt;e)C  
new TestMethod(); 6_,JW{#"  
} "!+gA&  
} Lq|>nY  
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